Elimination of admixtures from antibiotic sediments during their treatment with solvents

A model for determination of the admixture concentration in the secondary mother solution was developed. The concentration was determined depending on the solvent volume used for repulping the precipitate and on the impurity level of the initial antibiotic paste. When the values of X1 and X2 are known it is possible to estimate the amount of the admixtures remaining in the paste layer after separation of the secondary mother solution with regard to the volume of the latter in the precipitate pores. Optimization of paste repulping should be considered in combination with displacement washing and the apparatus used for separation of the phases, as well as the requirements for the purity level of the finished product.     

Elemental distribution in striated muscle and the effects of hypertonicity: Electron probe analysis of cryo sections

A method of rapid freezing in supercooled Freon 22 (monochlorodifluoromethane) followed by cryoultramicrotomy is described and shown to yield ultrathin sections in which both the cellular ultrastructure and the distribution of diffusible ions across the cell membrane are preserved and intracellular compartmentalization of diffusabler ions can be quantitated. Quantitative electron probe analysis (Shuman, H., A.V. Somlyo, and A.P. Somlyo. 1976. Ultramicros. 1:317-339.) of freeze-dried ultrathin cryto sections was found to provide a valid measure of the composition of cells and cellular organelles and was used to determine the ionic composition of the in situ terminal cisternae of the sarcoplasmic reticulum (SR), the distribution of CI in skeletal muscle, and the effects of hypertonic solutions on the subcellular composition if striated muscle. There was no evidence of sequestered CI in the terminal cisternae of resting muscles, although calcium (66mmol/kg dry wt +/- 4.6 SE) was detected. The values of [C1](i) determined with small (50-100 nm) diameter probes over cytoplasm excluding organelles over nuclei or terminal cisternae were not significantly different. Mitochondria partially excluded C1, with a cytoplasmic/ mitochondrial Ci ratio of 2.4 +/- 0.88 SD. The elemental concentrations (mmol/kg dry wt +/- SD) of muscle fibers measured with 0.5-9-μm diameter electron probes in normal frog striated muscle were: P, 302 +/- 4.3; S, 189 +/- 2.9;C1, 24 +/- 1.1;K, 404 +/- 4.3, and Mg, 39 +/- 2.1. It is concluded that: (a) in normal muscle the "excess CI" measured with previous bulk chemical analyses and flux studies is not compartmentalized in the SR or in other cellular organelles, and (b) the cytoplasmic C1 in low [K](0) solutions exceeds that predicted by a passive electrochemical distribution. Hypertonic 2.2 X NaCl, 2.5 X sucrose, or 2.2 X Na isethionate produced: (a) swollen vacuoles, frequently paired, adjacent to the Z lines and containing significantly higher than cytoplasmic concentrations of Na and Cl or S (isethionate), but no detectable Ca, and (b) granules of Ca, Mg, and P = approximately (6 Ca + 1 Mg)/6P in the longitudinal SR. It is concluded that hypertonicity produces compartmentalized domains of extracellular solutes within the muscle fibers and translocates Ca into the longitudinal tubules.     

Isolation of homogeneous polysaccharide monooxygenases from fungal sources and investigation of their synergism with cellulases when acting on cellulose

Lytic polysaccharide monooxygenases (PMO) discovered several years ago are enzymes classified as oxidoreductases. In nature, they participate in microbial degradation of cellulose together with cellulases that belong to the hydrolytic type of enzymes (class of hydrolases). Three PMO from ascomycetes–Thielavia terrestris, Trichoderma reesei, and Myceliophthora thermophila–were isolated and purified to homogeneous state using various types of chromatography. The first two enzymes are recombinant proteins heterologously expressed by the Penicillium verruculosum fungus, while the third is a native PMO secreted by M. thermophila. When acting on microcrystalline cellulose, all these PMOs displayed synergism with the cellulase complex of the P. verruculosum fungus. Replacing 10% of cellulases (by protein concentration) with PMO in the presence of 6.25 mM gallic acid or 2.5 μM of cellobiose dehydrogenase from M. thermophila, used as electron donors for PMO, resulted in the 17-31% increase in the yield of reducing sugars after 24-48 h of the enzymatic reaction.     

Relationship between dental morphology, sex, body length and age in Pontoporia blainvillei and Sotalia fluviatilis (Cetacea) in Northern Rio de Janeiro, Brazil

The relationship between dental morphology, sex, body length and age of small cetaceans can be used to determine ontogeny, sexual dimorphism and geographical variation. The objective of this study was to determine the relationship between dental morphology, sex, body size and age. A total of 91 specimens of P. blainvillei and 80 specimens of S. fluviatilis accidentally captured in fisheries or stranded in northern Rio de Janeiro (21 masculine37'-22 masculine25'S), from September 1988 to November 1996 were analysed. The teeth root diameter in P. blainvillei was significantly different between the sex; the values for females were larger than males. In neither species aid we observed significant in variations dimension and number of teeth, thickness of dentine and cemental layers and in the maximum width of cement as a function of body size. Age was related to increases in tooth length, root and cingulum diameters, and maximum width of cement in individuals of P. blainvillei, and tooth and crown lengths and maximum width of cement in individuals of S. fluviatilis. The observation of a linear growth between maximum width of cement and age in both species indicates that the equations obtained can be used to estimate relative age in P. blainvillei and S. fluviatilis in northern of Rio de Janeiro.     

Metabolic rate and directional nucleotide substitution in animal mitochondrial DNA

There is marked heterogeneity of nucleotide composition in mitochondrial DNA across divergent animals. Differences in nucleotide composition presumably reflect differences in directional nucleotide substitution for A+T or G+C nucleotides. In mitochondrial DNA, there is A+T directional nucleotide substitution in most (if not all) animals surveyed, and the magnitude of directional A+T nucleotide substitution differs greatly within and among groups. Differences in directional nucleotide substitution among lineages of mammals can be explained by changes in metabolic physiology. This relationship is thought to be mediated by the effect of oxygen radicals because these toxic compounds are by-products of aerobic metabolism and are known mutagens. Association between metabolism and nucleotide composition provides additional evidence in favor of the hypothesis that rates and patterns of nucleotide substitution in mitochondrial DNA can be influenced by factors that impinge on rates of endogenous DNA damage.      

Feruloyl esterase from aspergillus sp.: purification, properties, and action on natural substrates

An enzyme active toward the methyl ester of ferulic acid was isolated from the fungus Aspergillus sp. and purified to homogeneity using ion-exchange and hydrophobic chromatography. The molecular weight of the enzyme is 42 kD, and its pI is 3.7. The enzyme has a pH optimum in the range 4-6 and a temperature optimum in the range 40 to 60 degrees C. Using a number of synthetic and natural substrates, the enzyme was identified as a feruloyl esterase. The feruloyl esterase did not hydrolyze wheat straw. Ferulic acid was detected as a product of hydrolysis of wheat bran and sugar-beet pulp. Other products were also detected after sugar-beet pulp hydrolysis.     

3D FSPGR (fast spoiled gradient echo) magnetic resonance imaging in the diagnosis of focal cortical dysplasia in children

Small dysplastic lesions of the cerebral cortex are often missed by conventional MRI methods. The identification of subtle structural abnormalities by traditional multiplanar rectilinear slices is often limited by the complex convolutional pattern of the brain. We used a method of FSPGR (fast spoiled gradient-echo) of three-dimensional MRI data that improves the anatomical display of the sulcal structure of the hemispheric convexities. It also reduces the asymmetric sampling of gray-white matter that may lead to false-positive results. We present 5 from 12 patients with dysplastic cortical lesions in whom conventional two-dimensional and three-dimensional MRI with multiplanar reformatting was initially considered normal. Subsequent studies using 3D FSPGR identified various types of focal cortical dysplasia in all. These results indicate that an increase in the detection of subtle focal dysplastic lesions may be accomplished when one improves the anatomical display of the brain sulcal structure by performing 3D FSPGR.     

Selection of a Potent Bacillus licheniformis Strain Producing Thermostable Amylase

A highly potent strain of Bacillus licheniformis 103 that synthesized thermostable -amylase with temperature and pH optima of 90–95°C and 6.0–8.5, respectively, was obtained by mutagenesis and selection. The composition of fermentation media and conditions for submerged cultivation of the producer were optimized. -Amylase whose activity reached 260 U/ml was obtained in laboratory fermenters.