Pre-column derivatization of free bile acids for high-performance liquid chromatographic and gas chromatographic—mass spectrometric analysis

Pentachlorophenyl (PCP) esters of five free bile acids (FBA) were obtained by reacting the FBA and Kovacs' complex (KC) in a 1:8 molar ratio in acetone at 65°C, and were purified by column chromatography on silica gel. The esters were crystallized from benzene—hexane, derivatized as trimethylsilyl ethers for gas chromatography on a DB-1 capillary column and for gas chromatography—mass spectrometry with a DB-5 column, and mass spectrometry (MS) in the electron-impact (EI) positive-ion mode at 70 eV. The reaction is specific for FBA even in the presence of glycine and taurine conjugates of bile acids. The PCP esters were treated with benzylamine in chloroform or methanol to produce N-benzyl derivatives of FBA. The N-benzylamides were separated by high-performance liquid chromatography (HPLC) on a 4-μm Nova-Pak C₁₈ column, studied by thermospray—LC—MS, and in the direct insertion probe—EI positive-ion mode.     

Enhancement of Endogenous Release of Glutamate and γ-Aminobutyric Acid from Hippocampus CA1 Slices After In Vivo Long-Term Potentiation

The effect of long-term potentiation (LTP) on endogenous amino acid release from rat hippocampus slices was studied. LTP was induced in vivo by application of a tetanus (200 Hz, 200 ms) to the Schaffer collateral fibers in unanesthetized rats. Endogenous release of glutamate and gamma-aminobutyric acid (GABA) was investigated 60 min after tetanization in CA1 subslices of potentiated and control rats. No significant effects of LTP were observed in basal and K(+)-induced Ca(2+)-independent release components of these amino acids. In contrast, K(+)-induced Ca(2+)-dependent release of both glutamate and GABA increased approximately 100% in slices from potentiated rats. No differences were observed in total content of glutamate and GABA between the subslices from control and LTP animals. These results suggest a persistent increase in the recruitment of the presynaptic vesicular pool of glutamate and GABA during LTP.     

Effects of hydrostatic pressure on a membrane-enveloped virus: high immunogenicity of the pressure-inactivated virus.

A new approach to the preparation of antiviral vaccines relying on the inactivation of the virus particle by hydrostatic pressure is described. The enveloped virus vesicular stomatitis virus was utilized as a model; a pressure of 260 MPa applied for 12 h reduced infectivity by a factor of 10(4), and the antibodies against pressurized material were as effective as those against the intact virus when measured by their neutralization titer. Fluorescence measurements indicate that application of pressure results in perturbations of the particle interactions that permit binding of specific molecular probes. Electron microscopy showed that the membrane of the pressurized virus was partially preserved, presenting the spike pattern of the membrane G protein. Unlike the icosahedral viruses, dissociation into smaller particles was not observed, but a constant change in the morphology was the presence of a bulge in the surface of the pressurized virus, indicating a displacement of the capsid subunits, retained under the lipid and protein membrane.     

Water utilization of tropical hardwood hammocks of the Lower Florida Keys

Summary Predawn water potential of representative plant species, together with stable isotope composition of stem water and potential water sources were investigated in four low-elevation tropical hardwood hammocks in the Lower Florida Keys, during a one year period. Hammock species had the lowest water potentials when soil water content was low and/or soil salinity was high, but differences in groundwater salinity had no effect on the water potential. Comparison of D/H ratio of plant stem water with soil and ground water corroborates the conclusion that they are primarily utilizing soil water and not groundwater. Thus, tropical hardwood hammocks are buffered from saline groundwater, and are able to thrive in areas where groundwater salinity is as high as 25. The effect of sea level rise on these forests may depend more on changes in the frequency of tidal inundation of the soil surface than on changes in groundwater salinity.     

Some biological properties of the human amniotic membrane interferon.

Human amniotic interferon was investigated to define the species specificity of its antiviral action and to compare its anti-cellular and NK cell stimulating activities with those of other human interferons. The antiviral effect was titrated in bovine (RV-IAL) and monkey (VERO) cells. Amniotic interferon exhibited, in bovine cells, 5% of the activity seen in monkey cells, while alpha interferon displayed 200%. No effect was detected with either beta or gamma interferon in bovine cells. Daudi cells were exposed to different concentrations of various interferons and the cell numbers were determined. The anticellular effect of the amniotic interferon reached its peak on the third day of incubation. Results suggested a higher activity for alpha and gamma interferons and a lower activity for beta when compared to amniotic interferon. Using total mononuclear cells as effector cells and K 562 as target cells in a 51Cr release assay, it was demonstrated that low concentrations of amniotic interferon consistently stimulated NK cell activity in cells derived from several donors, the results indicating a higher level of activity with this interferon than with alpha and beta interferons.     

Living immobilized Acetobacter in Ca-alginate in vinegar production: Perliminary study on optimum conditions for immobilization

Summary The optimum conditions forAcetobacter immobilization were investigated. The results show that: 1) the maximum oxygen uptake rate (OURm) and cell release are related to alginate and cell concentration in the gel; 2)different alginate concentration does not affect cell viability, but long storage in CaCl₂ reduces the number of living cells; 3)the double alginate gel layers had no influence on cell viability and on the OURm and prevented cell leakage from the gel matrix.     

Insulin and progesterone increase 32PO4-labeling of phospholipids and inositol 1,4,5-trisphosphate mass in Xenopus oocytes.

After a 4-6 h induction period, insulin or progesterone induces Xenopus oocytes to enter prophase of meiosis. During the period of induction, both insulin and progesterone induced an increase in 32PO4 labeling of phosphatidylcholine and phosphatidylinositol. Through a mass assay, we found that insulin and progesterone increase inositol 1,4,5-trisphosphate (IP3) at about 15-30 s, 15 min and at about 2-3 h (0.5 GVBD50) after hormone addition. Since IP3 increases were small (from a basal of 66 to 104 nM), the results agree with prior conclusions that progesterone does not induce a large, cytosolic calcium elevation. Insulin is probably acting through the insulin-like growth factor-1 receptor as insulin concentrations greater than about 50 nM are required to increase IP3.     

Trehalase activity and its regulation during growth of Saccharomyces cerevisiae.

Trehalase activity decreased in 95% at the onset of the transition phase of growth of S. cerevisiae. The question which we raised was whether this phenomenon was due to proteolysis or to conversion of the enzyme to a less active form (dephosphorylation). Immunological methods allowed to identify the presence of the trehalase protein during cell growth. At the same stage of growth, an increase in the non-phosphorylated enzyme was detected "in vitro". Results utilizing mutant strains also indicated that regulation occurred by interconversion of forms. The same mechanism also seems to control trehalase activity in non proliferating conditions.     

In vitro propagation of Amaryllis belladonna

Amaryllis belladonna L. plants were multiplied successfully by means of tissue culture techniques. Different plant parts were tested as explant material, but plantlets could only be generated from the twin-scales and immature scapes. These in vitro-formed plantlets were divided into four parts and used for further multiplication. The twin-scale explants had the highest multiplication rate when a medium with 22.2 M benzyladenine and 0.54 M naphthaleneacetic acid was used. The sucrose concentration played an important role in the initiation of new plantlets, and the best results were obtained when a sucrose concentration of 2–3% was used. Anatomical observations were made during the initiation of the new plantlets.Abbreviations BA benzyladenine - NAA naphthaleneacetic acid - Benomyl (methyl [1-[(butylamino) carbonyl]-1H-benzimidazol-2-yl] carbamate) - Folpet (2-[(trichloromethyl)thio]-H-isoindole-1,3(2H)-dione phthalimide(I))