Elevation of Taurine in Hippocampal Extracellular Fluid and Cerebrospinal Fluid of Acutely Hypoosmotic Rats: Contribution by Influx from Blood?

Previous work has demonstrated that there is a selective increase in extracellular taurine in the brain during acute water intoxication. One aim of the present study was to investigate whether plasma taurine contributes to this increase. To this end, the concentrations of taurine, other amino acids, and ethanolamine (EA) were measured in plasma and CSF of urethane-anesthetized rats injected with 150 ml/kg body weight of distilled water. Blood pressure, blood gases, and pH, as well as plasma and CSF osmolality, were also measured. The CSF level of albumin was quantitated to study the function of the blood-CSF barrier. In separate experiments, hippocampal microdialysis was performed to determine the effects of acute plasma hypoosmolality on extracellular amino acids. Finally, the effect of water injection on hippocampal specific gravity and tissue amino acids was assessed. Blood gases and pH were essentially unchanged after water administration. Mean arterial blood pressure increased to peak levels approximately 50 mm Hg above control. Plasma osmolality decreased rapidly, whereas the depression of CSF osmolality was slower and less pronounced. The average volume of the hippocampus increased by 8%. Water injection was accompanied by a 25-fold elevation of taurine in plasma, whereas phosphoethanolamine (PEA) and EA increased moderately. A small fraction of the increase in plasma taurine might derive from blood cells because dilution of blood in vitro led to doubled plasma levels of the amino acid. Taurine, PEA, and EA increased consistently in CSF and hippocampal microdialysates. Plasma hypoosmolality transiently opened the blood-CSF barrier is reflected by augmented CSF concentrations of albumin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and characterization of two biologically active O-glycosylated forms of human parathyroid hormone produced in Saccharomyces cerevisiae. Identification of a new motif for O-glycosylation.

Expression and secretion of human parathyroid hormone in Saccharomyces cerevisiae were achieved by fusing a cDNA encoding the mature human parathyroid hormone (hPTH) to the preproregion of the yeast mating factor alpha. Purified hPTH from yeast-culture medium was found to contain, in addition to the native unglycosylated form, two mannosylated variants with different molecular masses. The three hPTH forms were processed identically, resulting in the same 84 amino acid polypeptides with amino acid sequences identical to the native hormone. In both the O-glycosylated forms that were separated by isocratic reverse-phase HPLC, two mannose-linked residues were localized to Thr79. In addition, the most glycosylated form showed a heterogeneous modification of three, four or five mannosyl residues linked at Ser66. Lysine is N-terminally located to Ser66 and probably stimulates this glycosylation, which introduces a possible new motif for O-glycosylation in yeast. The two glycosylated forms of hPTH had similar biological activity which was identical to the native form of hPTH in a hormone-sensitive adenylate cyclase assay in bone sarcoma cells. Thus, a C-terminal O-glycosylation of hPTH with up to seven mannosyl residues/molecule did not affect the biological activity of the hormone, making possible production of hPTH with potential different pharmacokinetic properties.     

Selenium in the central nervous system of rats exposed to 75-Sel-selenomethionine and sodium selenite

The aim of the present study is to investigate the accumulation and retention of organic and inorganic selenium in the central nervous system (CNS) of the rat. Selenium accumulation was investigated after oral treatment (3.0 mg Se/L drinking water) or ip injection (1.7 mg Se/kg body wt) of rats exposed to 75-Se L-selenomethionine (SeMeth) or sodium selenite (NaSe). Significant higher concentrations were observed after exposure to organic compared to inorganic selenium after oral as well as ip administration. Highest concentrations in both experiments were observed in cerebellum followed by the nearly identical levels in the cerebral hemisphere and spinal cord independent of the chemical form of selenium or the route of administration. The difference in concentrations observed between the different parts of the CNS investigated in each group were, however, not significant. Retention of selenium in the CNS was investigated after a single ip injection (1.7 mg Se/kg body wt) of 75-Se SeMeth or NaSe. In both groups, we observed an initial fast excretion phase followed by a slower excretion phase resembling a first-order reaction. Organic selenium disappeared much slower from all parts of the central nervous system compared to NaSe after a single injection.     

Neuropeptide Y modulates the action of vasodilator agents in guinea-pig epicardial coronary arteries

Recently, we have demonstrated that guinea-pig epicardial coronary arteries are supplied by numerous nerve fibres containing neuropeptide Y (NPY) immunoreactivity. However, examination of vasomotor responses revealed that NPY did not elicit a contractile response in these arteries. In contrast, acetylcholine (ACh), calcitonin gene-related peptide (CGRP), substance P and vasoactive intestinal polypeptide (VIP) all relaxed precontracted arteries. In the present study, we have used histochemical, immunohistochemical and in vitro pharmacological techniques, in order to further investigate the possible role of NPY in guinea-pig epicardial coronary arteries. A double-immunofluorescence staining technique revealed that CGRP and substance P were co-localized in nerve fibres distinct from those displaying NPY immunoreactivity. Furthermore, using a method combining immunofluorescence and histochemical techniques, we observed that putative cholinergic nerve fibres (identified by their acetylcholinesterase content) and NPY-immunoreactive nerve fibres are two different nerve populations. An in vitro pharmacological method demonstrated that NPY markedly inhibited the relaxant responses mediated by ACh, VIP, substance P and isoprenaline but had no effect on CGRP. These results suggest that NPY-containing nerves associated with guinea-pig epicardial coronary arteries may be predominantly involved in modulating the action of vasodilator agents.     

Flexibility in the donor substrate specificity of {beta} 1,4-galactosyltransferase: application in the synthesis of complex carbohydrates

Biosynthetically, bovine N-acetylglucosainine ß 1,4-galacto-syltransferase(GalT) catalyses the transfer of galactosyl residues from UDP-Galto the 4-position of GlcNAc units, resulting in the productionof N-acetyllactosamine sequences. UDP-Glc and UDP-GalNAc werealso found to act as donors for this enzyme, allowing the preparationof ßGlc(14)-ßGlcNAc and ßGalNAc(14)ßGlcNActerminating structures on the milligram scale. GalT could thusbe used to add ßGalNAc to ßGlcNAc(12)Manterminating structures, converting them to the ßGalNAc(14)ßGlcNAc(12)Mansequences found on glycoprotein hormones. GalT did not transferGlcNAc residues from UDP-GlcNAc, but it could utilize UDP-GlcNH₂as a donor. Synthesis of ßGlcNAc(14)ßGlcNAcsequences could therefore be accomplished by transfer of GlcNH₂from its UDP derivative, followed by N-acetylation of the productamino-disaccharide using acetic anhydride in methanol. The productsof the enzymatic reactions were characterized by ¹H-NMR-spectroscopyand fast-atom bombardment mass spectrometry. This work expandsthe scope of the combined chemical-enzymatic synthesis of complexcarbohydrates, using glycosyltrans-ferases, to the productionof oligosaccharides different from those for which these enzymeswere designed. These unnatural reactions should find applicationin glycoprotein and glycolipid remodelling. galactosyltransferase chemica1-enzymatic synthesis of oligosaccharides oligosaccharide analogues sugar-nucleotide analogues carbohydrate remodelling     

Isolation and characterization of noradrenalin storage granules of bovine adrenal medulla

A method is described for the preparation of (1) the heavy population of bovine adrenal chromaffin granules ($\text{S}{}_{\mathrm{<mtext>H</mtext>}}\text{(}\text{average sedimentation coefficient}\text{) = 12 400}\text{S}$ in 0.25 M sucrose) essentially free from contamination with mitochondria and other organelles, and (2) a subpopulation of this heavy population which is highly enriched in noradrenalin ($\text{?95\%}$ of the total catecholamine is noradrenalin). The method is based on isopycnic gradient centrifugation using a self-generating gradient of polyvinylpyrrolidone-coated colloidal silica particles (Percoll) in 0.5 M sucrose medium.The isolated population of noradrenalin granules appeared highly electron dense in transmission electron microscopy and revealed a rather narrow size distribution. The specific content of amine and adenine nucleotides (with reference to total granule protein) was markedly higher than for the total population of heavy chromaffin granules. The molar ratio of amines to adenine nucleotides was, however, lower in the noradrenalin granules, i.e. 4.8 vs. 11.9.     

Chironomid communities as water quality indicators

Recent mathematical indices summarizing biological communities of indicators are recapitulated. Improvements of these indices based on weighting according to width of trophic ranges of each species are suggested. Their principle deficiencies, however, are pointed out.
Revised lists of characteristic profundal as well as littoral and sublittoral chironomids in Nearctic and Palearctic lakes show that at least 15 characteristic chironomid species communities can be delineated, 6 in each of the oligotrophic and the eutrophic ranges and 3 in the mesotrophic range. It is proposed that these communities be lettered consecutively in the Greek alphabet from α (alpha) to o (omikron). A key to the 15 divisions based on the species associations in the profundal zone of harmonic lakes is put forward. There is very good correlation between the 15 divisions and the ratios of average total phosphorus to mean lake depth and average chlorophyll a to mean lake depth.
The ratio of chironomids to oligochaetes and the distribution patterns of single species have proven useful in pin-pointing localized areas of pollution. The primary mechanism governing the distribution of chironomid communities in oligotrophic and mesotrophic lakes appears to be the availability of food materials rather than the annual hypolimnetic oxygen concentration. In eutrophic lakes the relationships between organic matter accumulation and oxygen levels are so interdependent as to be inseparable.     

Interactions of the ring gland, overies, and juvenile hormone with brain neurosecretory cells in Musca domestica.

The staining intensity (median neurosecretory cell index) of the median neurosecretory cells (MNC) in Musca domestica increased as oögenesis progressed from stages 2 to 10. The amount of neurosecretory material within the MNC was dependent upon the presence of ovaries with developing or mature follicles. Ovariectomized flies had a median neurosecretory index that was 50 per cent less than that of control flies with mature eggs. In addition, we found that ring gland removal decreased the staining frequency of three different neurosecretory cell groups; increased staining frequency in another; increased the amount of neurosecretory material within the MNC fibre tract; increased the cytoplasmic area of types A and A′ MNC. Furthermore, neither the juvenile hormone analogue nor the ring gland had a direct effect on the median neurosecretory cell index but did influence neurosecretory activity indirectly by activating the ovaries. We hypothesize that an ovarian hormone—the oöstatic hormone—regulates either the release from or synthesis of neurosecretory material within the MNC.     

The morphogenesis of dimorphic pollen and anthers in Tripogandra amplexicaulis. Light microscopy and growth analysis

A characteristic of the genus Tripogandra is the presence of two dissimilar whorls of anthers. In T. amplexicaulis the short filamented anthers (S anthers) develop fertile, spheroidal pollen, the long filamented ones (L anthers) develop elongated spores, which degenerate prior to anthesis. Meiosis is regular in both types but occurs approximately two days later in the L anthers. Developmental traits of the L spores are a continuous, uniaxial extension and a sigmoid course of growth in volume accompanied by progressive vacuolarization and growth of starch grains and usually no division. The number of spores in the L anthers amounts to only 60 % of that in the S anthers, but the values for anther fresh weight and pollen sac volume of the former eventually exceed those of the latter and the relative growth rate in these variables is consistently higher in the L anthers. The relative rate in dry weight, however, is similar for both anthers and the absolute rate is clearly lower in the L anthers. These growth characteristics are reflected in a greater vacuolarization of both spores and the amoeboid tapetum in the L anthers. Cytological features of male sterile plants with hypotrophy of the tapetum are related to the sterility syndrome of the L anthers and a common hypothesis for the deviating features is presented.