Tumor size and karyometric variables in brain astrocytoma.

PURPOSE: To show any possible correlation of some karyometric variables with tumor size in patients with brain astrocytoma, in order to confirm karyometry as an objective histological method. PATIENTS AND METHODS: The study included 63 patients of different ages and both genders with brain astrocytoma histologically confirmed on the surgically removed material. In all patients maximal tumor excision was done, and all were postoperatively treated according to different therapeutic protocols. Tumor size (preoperative CT scan) was correlated with the duration of survival and the values of some karyometric tumor variables: area, density, maximal axis, mean axis, minimal axis, circumference, roundness, integrated optical density (IOD) and number of nuclei. RESULTS: Patients were separated into 3 groups according to the average tumor diameter. There were 34 cases of medium-sized tumors, 12 of small and 17 of large-sized tumors, and their respective survival was 83, 97 and 24 weeks. Patients with large tumors had statistically shorter survival compared to those with medium and small tumors (log-rank test, p=0.0122). Seven out of 9 examined karyometric variables were significantly related (p<0.05) to the tumor size: area, maximal axis, mean axis, minimal axis, circumference, roundness and IOD. CONCLUSION: Patients with larger tumors have shorter survival. The results of our morphometric analysis of the tumor cell nuclei, after correlation with CT findings, revealed that nuclear pleomorphism and larger nuclear size are associated with larger brain astrocytomas.

Chiral ligand-exchange chromatography as the screening method for proposed modifications in exametazime synthesis to enhance diastereoselectivity.

99M Tc (V)-d,l-HM-PAO complex is well-known radiopharmaceutical for regional cerebral blood flow imaging. The proposed modifications in exametazime, hexamethylpropyleneamine oxime (HM-PAO) (4,8-diaza-3,6,6,9-tetramethylundecane-2,10-dione bisoxime) synthesis, for reduction of intermediary reactant diiminebisoxime (DI) (4,8-diaza-3,6,6,9-tetramethylundecane-3,8-diene-2,10-dione bisoxime) concerned two reductants (NaBH(4) and KBH(4)), two solvents (ethanol and 2-propanol), and three mole ratios of reactant/reductants (1:1, 1:1.5, and 1:2). The simultaneous analysis of diastereo-enantiomeric HM-PAO content, as well as the content of starting DI, in different reduction mixtures were performed using chiral ligand-exchange chromatography (CLEC). The separation of the samples of investigated reduction mixtures, obtained in the second step of HM-PAO synthesis, has been accomplished by using an achiral sorbent (RP-18) and a chiral mobile phase (CMP) containing copper(II) complex with N,N-dimethyl-l-phenylalanine (l-DM-PhA) as initial complex for CLEC. With 12 different reduction conditions, the obtained ratios of diastereoisomers d,l-HM-PAO: meso-HM-PAO varied from 69.2:30.8 to 15.9:84.1, in comparison to the reduction in routine synthesis of HM-PAO which gives an equal mixture of diastereoisomers. The ternary mixed complexes formation recorded spectrophotometrically on addition of HM-PAO or DI to the mobile phase with binary complex Cu(l-DM-PhA)(2), due to the evidence of bathochromic shift of 46nm for lambda(max) with significant difference in absorptivity contributes to separation mechanism.

Chiral ligand-exchange chromatography for diastereo-enantio separation of exametazime.

The diastereo-enantio separation of isomeric mixtures of exametazime (HM-PAO) by liquid chromatography is described using an achiral sorbent (RP-18). A chiral eluent with the initial complex of Cu(II) and the optically active selector N,N-dimethyl-l-phenylalanine (l-DM-PhA), based on the ligand-exchange principle, has been applied. The separation is based on the presence of the immobilized binary complex Cu(l-DM-PhA)(2) and formation of mixed ternary complex. The optimal mole ratio of Cu(II):l-DM-PhA is 1:4, the pH should be between 4.1 and 4.2 and up to 0.8 mM of triethylamine is added for column presaturation with the initial complex. The elution order has been defined using isolated l-HM-PAO via l-HM-PAO L(+)tartrate and meso-HM-PAO obtained by repeated recrystallization from the isomeric mixture of HM-PAO. Complete resolution between all isomers (R(S) from 2.14 to 3.91) and partial resolution for meso(EE)/l-HM-PAO (R(S)=0.83) has been obtained. This means that the proposed chiral ligand-exchange chromatography (CLEC) can be used for determination of the isomeric purity of HM-PAO. This as an alternative method for resolution measurements with chiral columns.

Electrochemical study of cefetamet-Na and its polarographic determination.

Polarographic behavior of cephalosporin cefetamet-Na (Cef-Na) in aqueous solutions of pH ranging from 1.7 to 12.5 was investigated by applying direct current (dc) polarography, differential pulse polarography (dpp), alternating current (ac) polarography, cyclic voltammetry and electrolysis at constant potential. The characteristics of the corresponding electrode reaction are presented and discussed. The electrode reaction was found to be affected by strong adsorption, strongly and slightly pronounced in acidic and alkaline media, respectively. The methoxyimino group electroreduction was carried out and the mechanistic scheme was suggested. In addition, a sensitive dpp method was proposed for analytical determination of a very low concentrations of Cef-Na.

Acid-base equilibria in substituted 4-quinolone carboxylic acid solutions.

The protonation constants of some substituted 4-quinolone carboxylic acid anions (ofloxacin, pefloxacin and ciprofloxacin) were determined in lithium chloride solution of various concentrations at 293, 303 and 313 K using the pH-metric and spectrophotometric methods. The values of thermodynamic parameters (deltaG, deltaH and deltaS) for the first protonation step of these anions in 0.1M lithium chloride at 293 K, are reported. The formation of intramolecular hydrogen bonds is discussed.

Potentiometric determination of the protonation constants of 1,3-propanediamine-N,N'-diacetate-N,N'-di-3-propionate.

The protonation constants of 1,3-propanediamine-N,N'-diacetate-N,N'-di-3-propionate (1,3-pddadp) were determined in sodium nitrate solution of various concentrations and in 0.1M potassium nitrate medium. The values of the thermodynamic functions (DeltaG, DeltaH and DeltaS) for the successive protonation equilibria, in 0.1M (Na)NO(3) medium, at 25 degrees , are also reported.

Spectrophotometric determination of oxytetracycline in pharmaceutical preparations using sodium molybdate as analytical reagent.

A spectrophotometric method is proposed for the determination of oxytetracycline in pharmaceutical preparations. The method is based on the measurement of the absorbance of the molybdate-oxytetracycline complex at 404 nm (pH 5.50; mu = 0.1 M; 20 degrees C). The composition of the complex (1:1) was determined by the application of the spectrophotometric methods of Job and Bent-French (pH 5.50; lambda = 390 nm; mu = 0.1 M). The relative stability constant (K' = 10(4.6) of the complex was obtained by the methods of Sommer and Nash (pH 5.50; lambda = 390 nm; mu = 0.1 M; 20 degrees C). The molar absorptivity of the complex was 9.5 x 10(3) l mol-1 cm-1. Beer's law was obeyed over the concentration range 2.48-34.78 micrograms ml-1. The relative standard deviation RSD (n = 10) was 0.27-0.39%. The method proposed can be applied to the assay of oxytetracycline in capsules. The detection limit of oxytetracycline is 2.5 micrograms ml-1.

Spectrophotometric determination of pefloxacin in pharmaceutical preparations.

It has been established that the antibiotic pefloxacin (Abaktal) methanesulphonate reacts with Fe(III) at pH 1.00-8.00 to form a water-soluble complex with maximum absorbance at 360 nm. The composition of the complex, determined spectrophotometrically by the application of Job's, molar-ratio and Bent-French's methods, was pefloxacin: Fe(III) = 1:1 (pH = 2.50; lambda = 360 nm; mu = 0.1 M). The relative stability constant, obtained by the methods of Sommer and Asmus was 10(5.02) (pH = 2.50; lambda = 360 nm; mu = 0.1 M). The molar absorptivity of the complex at 360 nm was found to be 4.8 x 10(3) l mol-1 cm-1. Beer's law was followed for pefloxacin concentrations of 2.15-85.88 micrograms ml-1. The lower sensitivity limit of the method was 2.15 micrograms ml-1. The relative standard deviation (n = 10) was 0.57-1.07%. The method can be applied to the rapid and simple determination of pefloxacin in aqueous solutions and tablets.