A simple procedure to obtain one-micrometer sections of routinely embedded paraffin material

By freezing blocks of paraffin-embedded tissues to a convenient temperature it is possible to obtain routinely 1 micron sections that can be further processed as normal thicker sections. Normal and disposable steel knives can be used and the staining time should be increased in most procedures. Gradual freezing of blocks to the temperature of dry ice is the simplest and safest way to obtain an adequate temperature. The best results were obtained using as fixative 4% paraformaldehyde in phosphate buffered saline solution.     

Rare earth thiocyanate complexes with tripiperidinophosphine oxide: synthesis and characterization. Crystal structure of Pr(SCN)3(tpppO)3

The synthesis and characterization of rare-earth (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y) thiocyanate adducts with tripiperidinophosphine oxide (tpppO) with general formula (RE)(SCN)₃(tpppO)₃ are reported. Conductance measurements in acetonitrile indicate the non-electrolytic nature of the complexes. Infrared absorption spectra evidence that the SCN⁻ ion coordinates through the nitrogen atom (isothiocyanate form) and that tpppO coordinates through the phosphoryl oxygen. X-ray powder patterns suggest the existence of three different crystal forms: (1) La; (2) an isomorphous series including Ce, Nd and Pr; and (3) another isomorphous series, including Sm, Gd, Eu, Ho, Er, Tb, Lu and Y. The visible spectra of the Nd adduct and the calculated parameters β = 0.98, b^1/2 = 0.072 and δ = 1.06 indicate that the metal-ligand bonds are essentially electrostactic. The emission spectra of the Eu compound showed ⁵D₀ → ⁷F_J bands (J = 0, 1, 2), suggesting a C_3v symmetry for the coordination polyhedron. The lifetime of the ⁵D₀ state is 1.28 ms. The emission spectra of the Tb complex presented ⁵D₄ → ⁷F_J bands (J = 4, 5, 6) and the Dy complex showed the ⁴F_9/2 → ⁶H_13/2 band. The structure of the Pr complex showed that the coordination polyhedron is a trigonal antiprism, with the isothiocyanate anions in one base and three tpppO ligands in the other. Thermal analyses (TG-DTG) were carried out for the Ce, Nd and Gd adducts. Mass losses start between 250 and 334 °C. The final residues at 1300 °C are the corresponding phosphates.     

Esters of trehalose from Corynebacterium diphtheriae: A modified purification procedure and studies on the structure of their constituent hydroxylated fatty acids

The purification procedure of 6,6′-diesters of trehalose from Corynebacterium diphtheriae was modified and the isolated substance was analysed by mass spectrometry as its permethylated derivative. The fatty acid moiety released from the glycolipid after alkaline hydrolysis was studied by mass spectral analysis of the O-methylated and O-acetylated methyl ester derivatives. By argentation thin-layer chromatography, three species of O-acetylated methyl esters were recognized, corresponding to saturated, mono-unsaturated and di-unsaturated α-branched-β-hydroxylated fatty acids. The double bond was located by ozonolysis of the O-acetylated methyl ester derivatives, by gas chromatography of the reaction product and mass spectrometry of the effluent from the gas chromatograph. The main components of each species of α-branched-β-hydroxylated fatty acids found in the gly colipid fraction of C. diphtheriae were 2-tetradecyl-3-hydroxyoctadecanoic acid (C₃₂H₆₄O₃, corynomycolic acid), 2-tetradecyl-3-hydroxy-11-octadecenoic acid (C₃₂H₆₂O₃, corynomycolenic acid), 2-tetradec-7′-enyl-3-hydroxy octadecanoic acid (C₃₂H₆₂O₃) and 2-tetradec-7′-enyl-3-hydroxy-11-octadecenoic acid (C₃₂H₆₀O₃, corynomycoldienic acid). The glycolipid fraction from C. diphtheriae is obviously a complex mixture of 6,6′-diesters of trehalose.     

Active and passive respiratory mechanics in anesthetized dogs

In six spontaneously breathing anesthetized dogs (pentobarbital sodium, 30 mg/kg) airflow, volume, and tracheal and esophageal pressures were measured. The active and passive mechanical properties of the total respiratory system, lung, and chest wall were calculated. The average passive values of respiratory system, lung, and chest wall elastances amounted to, respectively, 50.1, 32.3, and 17.7 cmH2O X l-1. Resistive pressure-vs.-flow relationships for the relaxed respiratory system, lung, and chest wall were also determined; a linear relationship was found for the former (the total passive intrinsic resistance averaged 4.1 cmH2O X l-1 X s), whereas power functions best described the others: the pulmonary pressure-flow relationship exhibited an upward concavity, which for the chest wall presented an upward convexity. The average active elastance and resistance of the respiratory system were, respectively, 64.0 cmH2O X l-1 and 5.4 cmH2O X l-1 X s. The greater active impedance reflects pressure losses due to force-length and force-velocity properties of the inspiratory muscles and those due to distortion of the respiratory system from its relaxed configuration.     

Fluorescence properties of catecholamines in isolated storage organelles of adrenal medulla

THe quantum yield, the life time and the degree of polarization of the fluorescence of intact chromaffin granules isolated from bovine adrenal medulla were compared to those of catecholamines solutions and catecholamine/ATP mixtures. Rising concentrations of catecholamines in aqueous solutions exhibited increasing quenching and decreasing life times indicating that the quenching was collision induced. Similar effects occurred in mixtures of catecholamines with ATP and Ca²⁺ showing that the nucleotide did not remarkedly hinder the mobility of the catechol group. In suspensions of whole granules stron quenching and shortening of life time was observed compared with solutions of disrupted granules. Fluorescence yield and life time were decreased by about the same factor suggesting that storage of the amines was not correlated with a major immobilization of the catechol group. The degree of polarization of intact granules was higher than that of solutions of catecholamines alone, but similar to catecholamine/ATP mixtures with concentrations corresponding to those found in the granules. This indicates an interaction of catecholamines with ATP in the granules. The results are in agreement with a storage model for catecholamines in the chromaffin granules of adrenal medulla in which catecholamines are bound to ATP, but in a non-rigid way.