Simple and inexpensive Flow Injection Analysis for determination of sucrose using invertase and glucose oxidase immobilised on glass beads

A Flow Injection Analysis (FIA) for sucrose using invertase (E.C. 3.2.1.26), mutarotase (E.C.5.1.3.3) and glucose oxidase (E.C.1.1.3.4) was developed. The enzymes were immobilised on glass beads using glutaraldehyde. The sucrose concentration was related to oxygen saturation. Fall in O₂ concentration, as a result of sucrose oxidation, was detected by a low cost, home-made O₂ electrode. The system was able to measure sucrose from 0.025 to 100mM with a response time of 6min using 200 l of sample, with an apparent Km of 42mM of sucrose. The system has been operated satisfactorily for 50 days without loss any initial activity.     

Molecular cloning of major histocompatibility complex class II B gene cDNA from the Bengalese finch Lonchura striata

The only avian major histocompatibility complex (Mhc) genes thus far identified are from species of the relatively small order of Galliformes, while by far the largest order of Passeriformes (songbirds), containing some 60% of extant bird species, has not been studied at all in this regard. The Galliformes emerged more than 55 million years (my) ago, the Passeriformes some 25 my ago. Because of the potential for the use of Mhc genes as markers in the study of songbird populations, an attempt was made to clone class II B genes of a passeriform species, the Bangalese finch Lonchura striata acuticauda. Using a set of primers designed on the basis of known sequences, a probe corresponding to part of exon II was obtained by the polymerase chain reaction. The probe was then used to screen a Bengalese finch cDNA library and to isolate and sequence two nearly full-length clones. The sequences reveal the presence of one presumably functional class II B locus in this bird species.     

Environmental parameters affecting xylitol production from sugar cane bagasse hemicellulosic hydrolyzate by Candida guilliermondii

The bioconversion of xylose to xylitol by Candida guilliermondii FTI 20037 cultivated in sugar cane bagasse hemicellulosic hydrolyzate was influenced by cell inoculum level, age of inoculum and hydrolyzate concentration. The maximum xylitol productivity (0.75 g L⁻¹ h⁻¹) occurred in tests carried out with hydrolyzate containing 54.5 g L⁻¹ of xylose, using 3.0 g L⁻¹ of a 24-h-old inoculum. Xylitol productivity and cell concentration decreased with hydrolyzate containing 74.2 g L⁻¹ of xylose. Received 02 February 1996/ Accepted in revised form 15 November 1996     

Enantioselective analysis of praziquantel in plasma samples

A direct enantioselective high-performance liquid chromatography method is described for the quantitative determination of praziquantel enantiomers in plasma samples. The method involves two-step extraction of plasma with toluene, evaporation of the solvent and chromatography on a Chiralcel OD-H column using hexane-ethanol (85:15, v/v) as the mobile phase and detection at 220 nm. The assay satisfies all of the criteria required for use in clinical pharmacokinetic studies.     

Production of lipase free of citrinin by Penicillium citrinum

Lipase (Glycerol ester hydrolase E.G. 3.1.1.3) from a Brazilian strain of Penicillium citrinum free of the mycotoxin citrinin has been investigated. Citrinin production was inhibited by using culture medium containing olive oil, soybean oil and corn oil as carbon sources. Potassium concentration and pH play an important role in citrinin production. Potassium concentration lower than 30 mM and pH below 4.5 inhibited the mycotoxin production. P. citrinum produced lipase free of extraneous proteins and citrinin when cultured using, as nitrogen source, ammonium sulphate (lipase activity of 7.88 U/mg) and yeast extract (lipase activity of 4.95 U/mg) with olive oil as carbon source. This data is relevant to the larger scale production of lipases for food technology applications, from Penicillium citrinum.     

The effect of isoproturon on root growth and ultrastructure of the photosynthetic apparatus of two wheat cultivars and a weed

The effect of isoproturon [N,N-dimethyl N'4-(1-methyl-ethyl) phenyl urea] on the germination, growth of root and ultrastructure of the photosynthetic apparatus was investigated in two wheat cultivars ( Triticum sativum L. cvs Castan and Esquilache) and a weed ( Lolium rigidum Gaud.). No inhibition of germination was apparent in any of the three plants studied. The inhibition of root growth was considerably significant, especially in cv. Esquilache. After 48 h treatment with isoproturon (340 μ M ), the chloroplasts of the two wheat cultivars were found to be similar, showing a higher number of grana with fewer thylakoids per granum (lower stacking degree), broader grana stacks than in the control and an absence of starch. However, after 60 h of treatment, swelling of the thylakoids occurred in the Esquilache cultivar.
The rye grass was the most affected by the herbicide; at low concentration (3.4 μ M ) the number and size of the grana decreased considerably and the stroma thylakoids were destroyed. At higher concentration (17 μ M ), there was a strong accumulation in certain areas of the stroma of a substance with a lipid-like appearance, probably derived from the disintegrating thylakoids. At the same concentrations some chloroplast envelopes were completely desintegrated.
The Hill reaction of the three plants exhibited a similar sensitivity towards the herbicide.     

Initial characterization of the microenvironment that regulates connective tissue degradation in amniochorion during normal human labor.

Extracellular matrix degradation in fetal membranes leading to its rupture is coupled to myometrial activity and cervical ripening during human normal labor. Mechanisms which modulate collagen degradation in amniochorion during labor have not been elucidated. Initial characterization of the effect of different blood compartments on connective tissue degradation in amniochorion during human labor was explored. Amniochorion explants were stimulated with plasma of maternal venous blood, umbilical cord blood or placental blood, obtained from women with pregnancies at term, with or without labor. MMP-2 and MMP-9 activities were quantified in conditioned media by gelatin-zymography as an index of connective tissue degradation. Collagen content was measured in tissue explants and collagen fibrils distribution was examined by electron microscopy. Placental plasma from term pregnancies, with or without labor, is enriched with soluble signals that enhance the in vitro MMP-9 production by amniochorion. Accompanying ultrastructural distortion of collagen fibers and demonstration of collagen degradation fragments confirmed induction of extracellular matrix degradation. Control experiments in which MMP-9 activity was blocked with TIMP-1 resulted in inhibition of all the above mentioned changes. These results suggest that placental intervillous space is a functional compartment in which mediators capable to induce collagen degradation in amniochorion are selectively expressed during human labor.