D1 and D2 Dopaminergic Regulation of Acetylcholine Release from Striata of Freely Moving Rats

The effects of selective D1 and D2 dopaminergic agents on the extracellular acetylcholine (ACh) content in striata of freely moving rats were determined by the microdialysis technique. LY 171555, a selective D2 agonist, reduced ACh output by approximately 30% within 20 min at the dose of 0.2 mg/kg, i.p., whereas the D2 antagonists (-)-remoxipride (10 mg/kg, s.c.) and L-sulpiride (50 mg/kg, i.p.) induced maximal increases of approximately 50% within 10 and 20 min, respectively. In contrast, the D1 antagonist SCH 23390 (0.25 mg/kg, s.c.) decreased the extracellular ACh content by approximately 30% in 20 min, but lower doses--0.025 and 0.05 mg/kg--had no such effect. The stimulation of ACh release by LY 171555 was prevented by (-)-remoxipride but not by SCH 23390 (0.25 mg/kg, s.c.). In addition, the D1 agonist SKF 38393 failed to modify the ACh increasing effect of (-)-remoxipride. Thus, the D1 and D2 receptors subserve opposing functions on ACh release. The D1/D2 dopaminergic agonist R-apomorphine, at the does of 1 mg/kg, i.p., reduced ACh output by approximately 35% only when D1 receptors were blocked by SCH 23390 (0.025 mg/kg, s.c.). The results provide clear in vivo evidence of the tonic inhibition exerted by dopaminergic nigrostriatal input on the cholinergic system of the basal ganglia through D1 and D2 receptors.     

Development of photosystem-II activity during irradiance of etiolated Helianthus (Asteraceae) seedlings

Light-induced development of photosystem (PS)-II activity was followed during irradiance of etiolated Helianthus annuus (sunflower) cotyledons using chlorophyll a fluorescence. Cotyledons from seedlings grown in continuous darkness for 6 d were exposed to 100 μmol photons·m⁻²·s⁻¹ for time periods of 1, 3, 6, and 12 h. Associated with increased time of irradiance exposure were significant: (1) increases in concentration of PS II, (2) increases in quantum efficiency of PS II, (3) decreases in the ratio of PS-II quinone_B (Q_B)-nonreducing centers to total PS-II centers (PS-II Q_B-nonreducing centers + PS-II Q_B-reducing centers), and (4) decreases in the ratio of slow PS-II Q_B-reducing centers to total PS-II Q_B-reducing centers (fast PS-II Q_B-reducing centers + slow PS-II Q_B-reducing centers). The results support the hypotheses that development of PS II involves assembly of complexes which initially cannot reduce Q_B and that heterogeneous aspects of PS-II pools during chloroplast maturation may represent different developmental states.     

Biochemistry and molecular biology of exocellular fungal beta-(1,3)- and beta-(1,6)-glucanases

Many fungi produce exocellular beta-glucan-degrading enzymes, the beta-glucanases including the noncellulolytic beta-(1,3)- and beta-(1,6)-glucanases, degrading beta-(1,3)- and beta-(1,6)-glucans. An ability to purify several exocellular beta-glucanases attacking the same linkage type from a single fungus is common, although unlike the beta-1,3-glucanases, production of multiple beta-1,6-glucanases is quite rare in fungi. Reasons for this multiplicity remain unclear and the multiple forms may not be genetically different but arise by posttranslational glycosylation or proteolytic degradation of the single enzyme. How their synthesis is regulated, and whether each form is regulated differentially also needs clarifying. Their industrial potential will only be realized when the genes encoding them are cloned and expressed in large quantities. This review considers what is known in molecular terms about their multiplicity of occurrence, regulation of synthesis and phylogenetic diversity. It discusses how this information assists in understanding their functions in the fungi producing them. It deals largely with exocellular beta-glucanases which here refers to those recoverable after the cells are removed, since those associated with fungal cell walls have been reviewed recently by Adams (2004). It also updates the earlier review by Pitson et al. (1993).     

A comparison of taste thresholds for sweet and astringent-tasting compounds in great apes

Taste responses to fructose and tannic acid were compared between great apes using the 'two-bottle test' with tests of brief duration. The taste thresholds for fructose were [10-20] mM in Pongo pygmaeus, [40-50] mM in Pan troglodytes, and [70-80] mM in Gorilla gorilla. Inhibition thresholds for tannic acid were [2.9-3.5] mM in Pongo and [2.9-5.9] mM in Pan. Gorillas apparently significantly preferred tannins at low concentrations ([0.59-5.9] mM) but rejected concentrations above [8.8-14.7] mM. These results are discussed in relation to the effects of phylogenetic inertia and biological adaptation.     

Discussion on radioactive iodine treatment of hyperthyroidism and the risk of induced cancer

Iodine-131 (¹³¹I, radioiodine) has been used for over eight decades for the treatment of Graves’ disease, either as initial therapy or following failure of thionamides, as well as for the treatment of autonomous thyroid nodules. ¹³¹I treatment is simple to administer, effective, and relatively inexpensive. Recently, there has been some turmoil after a study published in JAMA Internal Medicine reported an increased risk of cancer from ¹³¹I treatment. The impact was of short duration however, as the paper received severe criticisms from many nuclear medicine physicians as well as from endocrinologists. Here we explain why that paper's conclusions are doubtful. We also review the major data on the topic of ¹³¹I therapy of hyperthyroidism and the risk of cancer.     

Differences in cell wall polysaccharides of several species of Eupenicillium

Abstract A β-(1–5)-galactofuran was isolated and characterized from fraction F1S (alkali- and water-soluble) of the cell wall of most of the species of Eupenicillium . In E. cryptum, E. euglaucum and E. nepalense the galactan contained galactofuranose with different linkages in addition to β-(1–5). Fraction F1I (alkali-soluble, water-insoluble) was an α-glucan in certain species while in other it was a =gb-glucan. Xylose was detected in some species in F1I or in F3 (alkali-soluble at 70°C). The most abundant fraction (F4), resistant to the alkali treatment, was a β-glucan-chitin complex. Excepting this component, the β-(1–5)-galactofuran was the polysaccharide which appeared more frequently in the cell wall of species of Eupencillium and it may have chemotaxonomic relevance.     

Use-wear analysis of the lithic assemblage from LGM Mohelno-Plevovce site (southern Moravia,Czech Republic)

The Mohelno-Plevovce site, located in Moravia (Czech Republic), has yielded two stone structures that represent the remains of two different short occupations. The chronology of these occupations situates them in the midst of the Last Glacial Maximum, and the techno-typological features of the lithic assemblages link them with the recently defined ‘Epi-Aurignacian with Sagaidak–Muralovka-type microliths’. High power use-wear analysis of representative lithic samples from the two stone structures has been carried out to understand site function and the particular uses made of the different tool types represented at the site. The results of the use-wear analysis are used to test whether these occupations represent the archaeological signatures of pioneer populations that reoccupied the Moravia region, which had previously been abandoned by human populations due to the climatic hardships of the Last Glacial Maximum.     

Isolation and Identification of α-(γ-Aminobutyryl)-Hypusine

A new dipeptide, alpha-(gamma-aminobutyryl)-hypusine, was identified in bovine brain. This compound was isolated from trichloroacetic acid-soluble fraction of bovine brain with five steps of ion-exchange chromatography. Its structure was postulated by routine chemical analyses and determined by synthesis. The amount of the compound isolated from 1.2 kg of bovine brain was 870 nmol.     

Culture conditions affect the chemical composition of the exopolysaccharide synthesized by the fungus Aureobasidium pullulans

Aims:  To identify if culture conditions affect the chemical composition of exopolysaccharide (EPS) produced by Aureobasidium pullulans .
Methods and Results:  In batch airlift and continuously stirred tank (CSTR) reactors the EPS produced with low (0·13 g l⁻¹ N) initial NaNO₃ or (NH₄)₂SO₄ levels contained pullulan, with maltotriose as its major component, similar to that synthesized in the airlift reactor with high (0·78 g l⁻¹ N) initial NaNO₃ levels. EPS produced by CSTR grown cultures with high (NH₄)₂SO₄ levels contained little pullulan, possibly because of a population shift from unicells to mycelium. This chemical difference may explain why total EPS yields did not fall as they did with cultures grown under identical conditions with high NaNO₃ levels, where the pullulan component of the EPS disappeared. EPS synthesized in N-limiting chemostat cultures of A. pullulans changed little with growth rate or N source, being predominantly pullulan consisting of maltotriose units.
Conclusions:  While the EPS chemical composition changed little under N-limiting conditions, high initial medium N levels determined maltotriose content and/or pullulan content possibly by dictating culture morphology.
Significance and Impact of the Study:  These results emphasize the requirement of all studies to determine EPS chemical composition when examining the influence of culture conditions on EPS yields.     

Polymerization of Soybean 11S Globulin Due to Reactions with Peroxidizing Linoleic Acid

Soybean 11S globulin was polymerized by incubating with peroxidizing linoleic acid. The molar ratio of the acidic subunits to the basic subunits of 11S globulin decreased with the elapse of the incubation time. The acidic subunits were lost faster and formed polymers more easily than the basic subunits. The acidic and basic subunits in 11S globulin were fractionated by DEAE-Sephadex gel chromatography. Each of the acidic and basic subunits was allowed to react with peroxidizing linoleic acid individually. The results also showed that the acidic subunits formed polymers faster than the basic subunits. Both succinylated and acetylated 11S globulins were also submitted to the incubation with peroxidizing linoleic acid. The polymerization of the modified protein was suppressed by masking ε-amino groups.     

Is the deciduous/permanent molar enamel thickness ratio a taxon-specific indicator in extant and extinct hominids?

In Primates, enamel thickness variation stems from an evolutionary interplay between functional/adaptive constraints (ecology) and the strict control mechanisms of the morphogenetic program. Most studies on primate enamel thickness have primarily considered the permanent teeth, while the extent of covariation in tooth enamel thickness distribution between deciduous and permanent counterparts remains poorly investigated. In this test study on nine extant and fossil hominids we investigated the degree of covariation in enamel proportions between 25 pairs of mandibular dm2 and M1 by a so-called “lateral enamel thickness diphyodontic index”. The results did not provide an unambiguous picture, but rather suggest complex patterns likely resulting from the influence of many interactive factors. Future research should test the congruence of the “diphyodontic signal” between the anterior and the postcanine dentition, as well as between enamel and the enamel-dentine junction topography.     

Taxonomy of subgenus Temnoclemmys Bergounioux, 1958 (Testudines: Geoemydidae: Ptychogasterinae) based on new material from the Vallès-Penedès Basin (NE Iberian Peninsula)

The taxonomy of the freshwater turtle subgenus Ptychogaster (Temnoclemmys) (Testudines, Geoemydidae, Ptychogasterinae) is revised based on new and previously-published material from the Vallès-Penedès Basin (NE Iberian Peninsula). Additional remains of subgenus Ptychogaster, first reported from this basin, are also described. Although the oldest remains of Temnoclemmys are left unassigned, most of the available remains are attributed to its type species, Ptychogaster (Temnoclemmys) batalleri, originally described from the Late Miocene (MN9 and MN10) of this basin. The new material expands the chronostratigraphic range of P. batalleri in the Vallès-Penedès Basin back to the MN7 + 8 and shows that “Testudo” celonica is its junior synonym. Emended diagnoses for Ptychogaster and Temnoclemmys are also provided.     

Distribution of α-(γ-Aminobutyryl)-Hypusine

The distribution of alpha-(gamma-aminobutyryl)-hypusine was examined in several organs of the rabbit and in the brain of the rat, rabbit, dog, ox, and monkey. The peptide occurred only in the brains, but appeared to be absent from dog brain. Concentrations were higher in the cerebral hemispheres than in other portions of the brain. No significant difference between white and gray matter was observed.     

Influence of secondary structure on the decay kinetics of fluorescent donor-acceptor labelled peptides

Time-resolved fluorescence decays from a series of methoxynaphthalene labelled peptides in ethyl acetate were monitored over the temperature range −40 to 60°C. The quenching effect of a piperidone acceptor group placed at various positions along the peptide chain relative to the fluorescent methoxynaphthalene donor was studied. In this moderately polar solvent the mechanism of quenching is most likely electron transfer, although a Dexter exchange mechanism cannot be ruled out. Both donor and acceptor moieties were covalently attached to the side-chains of glutamic acid residues. These were either placed adjacently, in the case of a dipeptide, or separated by three and six amino acids within a 12 and 15 amino-acid oligopeptide, respectively. The presence of the piperidone group resulted in a reduction in the fluorescence lifetime and a change from a simple monoexponential decay to more complex behaviour. This was found to vary reversibly with temperature and not to be caused by impurities. Modelling of the fluorescence decays was carried out using either the sum of two exponentials or a distribution of decays. For the dipeptide the best fit was a distribution while in the case of the 12-mer two clearly distinguishable populations could be observed. The results for the 15-mer were equivocal. Importantly, regardless of the fitting method used the quenching rate was found to be fastest for the 12-mer. The slower quenching rates observed for the dipeptide compared to the oligopeptides provide strong evidence that secondary structure promotes better electronic coupling between the donor and acceptor. The biexponential fluorescence behaviour for the 12 amino-acid oligopeptide is ascribed to two slowly (>10ns) interconverting conformational states. Comparison with circular dichroism and infrared obtained in acetonitrile indicates these two conformers are likely to be an -helix and a 3(10)-helix with electronic coupling strongest in the latter case.     

Pyrenocine C,A phytotoxin-related metabolite produced by onion pink root fungus,Pyrenochaeta terrestris

The structure of pyrenocine C, a new metabolite isolated from onion pink root fungus, Pyrenochaeta terrestris (Hansen) has been elucidated as (±)-(2′E)-5-(1′-hydroxybut-2′-enyl)-4-methoxy-6-methyl-2-pyrone by spectroscopic methods and chemical correlation with pyrenocine A.     

β-Hydroxybutyrate as a Precursor to the Acetyl Moiety of Acetylcholine

Abstract— Rat brain cortex slices were incubated with 10 mm -glucose and trace amounts of [6-³H]glucose and [3-¹⁴C]β-hydroxybutyrate. The effects of (-)-hydroxycitrate, an inhibitor of ATP-citrate lyase; methylmalonate, an inhibitor of β-hydroxybutyrate dehydrogenase; and increasing concentrations of unlabeled acetoacetate were examined. The incorporation of label into lactate, citrate, malate, and acetylcholine (ACh) was measured and ³H:¹⁴C ratios calculated. Incorporation of [¹⁴C]β-hydroxybutyrate into lactate was limited because of the low activity of gluconeogenic enzymes in brain, whereas incorporation of ¹⁴C label into Krebs cycle intermediates and ACh was higher than in previous experiments with [³H-,¹⁴C]-glucose. (–)-Hydroxycitrate (5.0 m^M) reduced incorporation of [³H]glucose and [¹⁴C]β-hydroxybutyrate into ACh. In contrast, slices incubated with methylmalonate (1 mm ) showed a decrease in ¹⁴C incorporation without appreciably affecting glucose metabolism. The effects of high concentrations of methylmalonate were nonselective and yielded a generalized decrease in metabolism. Acetoacetate (1 mm ) also produced a decreased ¹⁴C incorporation into ACh and its precursors. At 10 mm , acetoacetate reduced ³H and ¹⁴C incorporation into ACh without substantially affecting total ACh content. From the results, it is suggested that in adult rats β-hydroxybutyrate can contribute to the acetyl moiety of ACh, possibly via the citrate cleavage pathway, though it is quantitatively less important than glucose and pyruvate. This contribution of ketone bodies could become significant should their concentration become abnormally high or glucose metabolism be reduced.     

Alkaloid and lignan constituents of Cinnamosma madagascariensis

A new lignan glycoside, 5-methoxy-9-β-xylopyranosyl-(-)- isolariciresinol and two indole alkaloids have been characterised from the bark of Cinnamosma madagascariensis.     

新型乙酰胆碱酯酶抑制剂Bis(9)-(-)-Meptazinol的小鼠 和大鼠药代动力学研究

目的:研究新型乙酰胆碱酯酶(acetylcholinesterase,AChE)抑制剂Bis(9)-(-)-Meptazinol(B9M)在小鼠和大鼠体内的药代动力学、组织分布和排泄过程。方法:应用本课题组前期报道的大鼠血浆中B9M的LC-MS/MS定量方法:检测B9M皮下和静脉给药后小鼠血浆和脑组织中的含量,计算相应的药代动力学参数,测定B9M小鼠(1.5 mg/kg)和大鼠(1.0 mg/kg)皮下给药后不同时间点的组织分布和粪便、尿液中排泄量。结果:小鼠经皮下注射后,B9M可迅速进入血液(Tmax=0.25 h)血液中消除速度较慢(T_(1/2)=18.09h)绝对生物利用度为115.95%。皮下注射后,B9M在脑内的达峰时间和半衰期分别是8h和18.75h,生物利用度为44.67%。小鼠和大鼠皮下给药后广泛分布于各组织,以脾、肺、肾等血流量大的组织中分布最多。B9M从体内排泄迅速原型药物在小鼠和大鼠尿液和粪便中的排泄量低于3%。结论:皮下给药B9M在小鼠和大鼠体内具有易吸收、分布广泛、易排泄的特点药代动力学特征优良,是极具研发潜力的抗阿尔茨海默病(Alzheimer's disease,AD)新药。