Defective remethylation of homocysteine is related to decreased synthesis of coenzymes B2 in thyroidectomized rats

Summary. We investigated the influence of hypothyroidism on homocysteine metabolism in rats, focusing on a hypothetical deficient synthesis of FAD by riboflavin kinases. Animals were allocated in control group (n=7), thyroidectomized rats (n=6), rats with diet deficient in vitamin B2, B9, B12, choline and methionine (n=7), thyroidectomized rats with deficient diet (n=9). Homocysteine was decreased in operated rats (2.6±1.01 vs. 4.05±1.0mol/L, P=0.02) and increased in deficient diet rats (29.56±4.52 vs. 4.05±1.0mol/L, P=0.001), when compared to control group. Erythrocyte-Glutathione-Reductase-Activation-Coefficient (index of FAD deficiency) was increased in thyroidectomized or deficient diet rats (P=0.004 for both). Methylenetetrahydrofolate-reductase and methionine-synthase activities were decreased in thyroidectomized rats but not in those subjected to deficient diet. Cystathionine--synthase was increased only in operated rats. Taken together, these results showed a defective re-methylation in surgical hypothyroidism, which was due in part to a defective synthesis of vitamin B2 coenzymes. This defective pathway was overcompensated by the increased Cystathionine--synthase activity.     

Interactions of Aβ(1–40) with Glycerophosphocholine and Intact Erythrocyte Membranes: Fluorescence and Circular Dichroism Studies

Deposition of amyloid peptide in human brain in the form of senile plaques is a neuropathological hallmark of Alzheimers disease (AD). Levels of a phospholipid breakdown product, glycerophosphocholine (GPC), also increase in AD brain. The effect of GPC on amyloid (1–40) peptide (A) aggregation in PBS buffer was investigated by circular dichroism and fluoresence spectroscopy; interactions of A and GPC with the intact erythrocyte membrane was examined by fluoresence spectroscopy. Fluorescamine labeled A studies indicate GPC enhances A aggregation. CD spectroscopy reveals that A in the presence of GPC adopts 14% more -sheet structure than does A alone. Fluorescamine anisotropy measurements show that GPC and A interact in the phospholipid head-group region of the erythrocyte membrane. In summary, both soluble A and GPC insert into the phospholipid head-group region of the membrane where they interact leading to -sheet formation in soluble A which enhances A aggregation.     

Homocysteine stimulates the expression of monocyte chemoattractant protein-1 in endothelial cells leading to enhanced monocyte chemotaxis

The effect of intraperitoneal administration of tocopherol (100 mg/kg wt/24 h) on ascorbate (0.4 mM) induced lipid peroxidation of mitochondria and microsomes isolated from rat liver and testis was studied. Special attention was paid to the changes produced on the highly polyunsaturated fatty acids C20:4 n6 and C22:6 n3 in liver and C20:4 n6 and C22:5 n6 in testis. The lipid peroxidation of liver mitochondria or microsomes produced a significant decrease of C20:4 n6 and C22:6 n3 in the control group, whereas changes in the fatty acid composition of the tocopherol treated group were not observed. The light emission was significantly higher in the control than in the tocopherol treated group. The lipid peroxidation of testis microsomes isolated from the tocopherol group produced a significant decrease of C20:4 n6 , C22:5 n6 and C22:6 n3, these changes were not observed in testis mitochondria. The light emission of both groups was similar. The treatment with tocopherol at the dose and times indicated showed a protector effect on the polyunsaturated fatty acids of liver mitochondria, microsomes and testis mitochondria, whereas those fatty acids situated in testis microsomes were not protected during non enzymatic ascorbateFe²⁺ lipid peroxidation. The protector effect observed by tocopherol treatment in the fatty acid composition of rat testis mitochondria but not in microsomes could be explained if we consider that the sum of C20:4 n6 + C22:5 n6 in testis microsomes is 2-fold than that present in mitochondria.     

Inhibition of protein synthesis enhances the lytic effects of tumor necrosis factor α and interferon γ in cell lines derived from gynecological malignancies

Summary Few clinical responses have occurred in preliminary studies using the cytokines tumor necrosis factor (TNF) or interferon (IFN) in cancer patients. This may be related to the observation that many malignant cell lines are resistant to lysis by these cytokinesin vitro. Resistance to lysis by TNF or IFN in many cells is controlled by a protein-synthesis-dependent mechanism, such that when protein synthesis is inhibited cells become sensitive to lysis by these cytokines. Because there is some evidence that TNF and IFN act through different lytic mechanisms and are opposed by different resistance mechanisms, we treated a panel of eight cell lines, five derived from human cervical carcinomas (ME-180, MS751, SiHa, HT-3, and C-33A) and three derived from ovarian carcinomas (Caov-3, SK-OV-3, and NIH: OVCAR-3) with both TNF and IFN to determine whether such combination treatment might maximizein vitro cell lysis. Our results showed that pretreatment with IFN followed by exposure to TNF in the presence of protein synthesis inhibitors increased lysis of seven of the eight cell lines above that seen with either TNF or IFN and inhibitors of protein synthesis. Only the cell line C-33A was resistant to lysis by TNF and IFN, when exposed to these agents both alone and in combination with protein synthesis inhibitors. Clinically, combining the cytokines TNF and IFN with protein synthesis inhibitors may maximize thein vivo lytic effects of these cytokines.Supported by American Cancer Society Career Development Award 90-221     

Comparative Study of Effects of Various Sterols and Triterpenoids on Permeability of Model Lipid Membranes

Using permeability to labeled glucose as a criterion of stability for liposomal membranes, a comparative study on stabilizing properties of different sterols and triterpenes in phospholipid bilayer has been carried out as well as on structural peculiarities of sterols responsible for membranolytic properties of cucumarioside G₁ from the cucumaria Eupentacta fraudatris. Stabilizing action of the studied sterols and triterpenoides incorporated in the bilayer decreases in the following order: cholesterol sulfate > cholesterol > ⁵-sterols > -sitosterol > ergosterols > ⁷-sterols > epicholesterol > pregnane > androstane > coprosterol > 14-methylcholest-9(11)-en-3-ol > 4, 14-dimethylcholest-9(11)-en-3-ol > holothurinogenin A₁ > glucoside of cholesterol > -xylosidase of ⁷-sterols > betulin > protopanaxatriol > phosphatidylcholine liposomes without sterol > protopanaxadiol > oleanolic acid. Sterol-dependent membranolytic cucumarioside G₁ practically loses its ability to increase permeability of phospholipid membranes containing sterols obtained from this holothuria as well as coprosterol, epicholestrol, sulfated and glycosylated forms of sterols. The obtained results confirm the sterol hypothesis of the mechanism of membranotropic action of holothuria glycosides and of resistance to them of holothuria cell membranes.     

Synchrone Vorgänge in asynchron sprossenden Saccharomyces-Kulturen: Mutationsauslösung und Abtötung durch Acridine

Zusammenfassung Das Aushungern der Hefezellen in Aq. deion. führt zu einer Gleichschaltung gewisser physiologischer Prozesse. Trotz asynchroner Sprossung erfolgt eine rhythmische Abnahme der Acridinorange-Toxicität sowie eine gehäufte Entwicklung atmungsdefekter Mutanten zu einem bestimmten Zeitpunkt.

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Summary Starvation of yeast cells in aq. deion. tends to synchronize some physiological processes. In spite of an asynchronous budding there follows a rhythmic decrease in acridine organge toxicity and a single maximum in the development of respiration deficient mutants.

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Vorläufige Mitteilung     

Role of mitochondria in ethanol tolerance of Saccharomyces cerevisiae

The presence of active mitochondria and oxidative metabolism is shown to be essential to maintain low inhibition levels by ethanol of the growth rate (), fermentation rate (v) or respiration rate () of Saccharomyces cerevisiae wild type strain S288C. Cells which have respiratory metabolism show K _i (ethanol inhibition constant) values for , v and , higher (K _i>1 M) than those of petite mutants or grande strains grown in anaerobiosis (K _i=0.7 M). In addition, the relationship between or v and ethanol concentration is linear in cells with respiratory metabolism and exponential in cells lacking respiration. When functional mitochondria are transferred to petite mutants, the resulting strain shows K _i values similar to those of the grande strain and the inhibition of and v by increasing ethanol concentrations becomes linear.     

Primary structure of the hemoglobin beta-chain of rose-ringed parakeet (Psittacula krameri)

The primary structure of Rose-ringed Parakeet hemoglobin -chain was established, completing the analysis of this hemoglobin. Comparisons with other avian -chains show variations smaller than those for the corresponding -chains. There are 11 amino acid exchanges in relationship to the only other characterized psittaciform -chain, and a total of 35 positions are affected by differences among all avian -chains analyzed (versus 61 for the -chains). At three positions, the Psittacula -chain has residues unique to this species. Three ₁₁ contacts are modified, by substitutions at positions 51, 116, and 125.     

A comparison of male and female recombination frequency in wheat using RFLP maps of homoeologous group 6 and 7 chromosomes

A novel approach was used to compare male and female recombination rates in wheat. Doubled haploid lines were developed from an F₁ using two distinct approaches: the anther-culture technique and the Hordeum bulbosum system, from which sets of lines were developed from male and female meioses, respectively. The genotype of the lines was established at RFLP and isozyme markers polymorphic on chromosomes of homoeologous groups 6 and 7, and male and female linkage maps were calculated using this information. The markers in one segment of chromosome 6B exhibited disturbed segregation frequencies in the anther-culture population. The male and female maps differed significantly in recombination frequency between some markers on two chromosomes, and these were consistent in direction within chromosomes and inconsistent in direction between chromosomes. In two of the four chromosomes studied the male map was much longer than the female map. These results suggest that significant differences may exist in male and female recombination frequencies in bread wheat which are specific to certain chromosomal segments but are inconsistent in direction between chromosomes. Other factors, such as environmental influences, may also be important in creating differences.     

Factors affecting facultative polygyny and breeding results in the Great Reed Warbler (Acrocephalus arundinaceus)

Summary In a population of Great Reed Warbler (42–53 stationary males) the sex ratio was balanced and occurence of polygynous males (on average 15 % of the males) was more or less compensated by respective number of unmated males. Prospective polygynists arrived earlier in spring on average than monogamists, and got the first female quicker. Their territories were larger (statistically insignificant) and more often situated close to good foraging grounds. The reeds around primary female nests were on average thicker (and taller) and not so dense as in the case of monogamous, secondary and tertiary females. The intensity of nestling feeding (no. of visits per nestling per hour) was higher in the nests of monogamous females, than in primary females, and lowest in secondary and tertiary females nests. Nestlings in secondary and tertiary female broods were on average lighter than in monogamous and primary female broods. The male helped feed nestlings in secondary female nest only exceptionally. In monogamous situation their share in feeding was ca. 50%, and less so in primary female nests. Production of fledglings per female was highest in primary females and lowest in secondary and tertiary females, mainly due to the high starvation rate in the nests of secondary and tertiary females. Generally, collected data strongly suggest that female choice is determined by territory quality, and polygyny threshold hypothesis cannot be rejected. The deception hypothesis cannot be rejected as well in some observed special situations (disruptive territories or polyterritoriality; four cases).

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Voraussetzungen für fakultative Polygynie beim Drosselrohrsänger (Acrocephalus arundinaceus)

Zusammenfassung Das Geschlechterverhältnis in der untersuchten Drosselrohrsänger-Population von 42 bis 53 war ausgeglichen. Das Auftreten polygyner (durchschnittlich 15 % der ) wurde mehr oder weniger durch eine entsprechende Anzahl unverpaarter kompensiert. Prospektiv polygyne kamen durchschnittlich früher an als monogame und waren schneller verpaart. Ihre Reviere waren (statistisch nicht signifikant) größer und lagen näher zu günstigen Nahrungsgebieten. Das Schilf in der Nähe der Nester von Erst- war durchschnittlich dicker (und höher) als und nicht so dicht wie bei Einzel- oder Zweit- und Dritt- . Die Fütterungsfrequenz der Nestlinge (Anzahl der Besuche beider Altvögel mit Futter pro Nestling pro Stunde) war bei Nestern von Einzel- höher als bei Erst- und am niedrigsten bei Nestern von Zweit- und Dritt-. Nestlinge von Zweit- und Dritt- waren durchschnittlich leichter als solche von Einzel-und Erst- . halfen nur ausnahmsweise bei der Fütterung von Nestlingen von Zweit- . Bei monogamen Paaren beteiligten sich die ungefähr zur Hälfte an der Fütterung der Nestlinge, bei Nestern von Erst- in geringerem Umfang. Der Ausfliegeerfolg war am höchsten beim Erst- und am niedrigsten bei Zweit- und Dritt- , hauptsächlich bedingt durch Verhungern der Nestlinge. Allgemein legen die Daten nahe, da\ die die nach der Revierqualität auswählen und daß das Polygynieschwellenmodell vonOrians undVerner nicht abgelehnt werden kann. Einige Beobachtungen stützen die Hypothese, daß in bestimmten Situationen (unübersichtliche Reviere, Polyterritorialität) durch Täuschung polygyn werden.

     

Purification and characterization of aspartate aminotransferase from developing embryos of the camel tick Hyalomma dromedarii

Aspartate transaminase (AST) activity in the camel tick Hyalomma dromedarii was followed throughout embryogenesis. During purification of AST to homogeneity, ion exchange chromatography lead to four separate forms (termed I, II, III and IV). AST II with the highest specific activity was pure after chromatography on Sephacryl S-300. The molecular mass of AST II was 52KDa for the native enzyme, composed of one subunit of 50KDa. AST II had a Km value of 0.67mM for -ketoglutarate and 15.1mM for aspartate. AST II had a pH optimum of 7.5 with heat stability up to 50°C for 15min. The enzyme was activated by MnCl₂, and inhibited by CaCl₂, MgCl₂, NiCl₂, and ZnCl₂.     

Endocrine cells in the human fetal small intestine

Summary In this report we describe the time of appearance and ultrastructural features of enteroendocrine cells (EECs) in the human fetal small intestine (SB) between 9 and 22 weeks gestation. Thirteen distinctive EECs were identified in fetal SB. Two of these, not found in normal adult SB, appeared within the stratified epithelium of the proximal SB at 9–10 weeks. They were arbitrarily termed primitive and precursor cells. As in all fetal EECs, the pale cytoplasm of the primitive cell contains a distinctive population of secretory granules (SGs). Primitive cell SGs average 200–330 nm; some have dense cores with lucent halos while others are filled with a homogeneous dense or flocculent material. The SGs of the precursor cells are larger, averaging up to 1 m in diameter and their contents vary in electron density. A third group of cells not described in normal adult SB was arbitrarily termed transitional cells. These have two populations of SGs; one resembles the SGs of the precursor cells, and the other resembles the SGs of some of the specific adult type EECs. Transitional EC, S, I and G cells are seen. In addition, mature appearing EC, S, G, I, L, D, and D₁ cells were identified by 12 weeks of gestation. The primitive, precursor, and transitional cells may represent sequential developmental precursors of adult type EECs.Supported by Research Grant AM-17537 from the National Institutes of Health, Besthesda, MarylandThe authors would like to thank Ms. Linda Barstein for her excellent technical assistance     

Structural studies of the glycopeptides of B-chain of cinnamomin – a type II ribosome-inactivating protein by nuclear magnetic resonance

Cinnamomin is a plant type II ribosome-inactivating protein (RIP) isolated from the seeds of Cinnamomum camphora. It consists of two nonidentical polypeptide chains (A- and B-chain) held together through one disulfide linkage. Its A- and B-chain contain 0.3% and 3.9% sugars respectively. The B-chain of cinnamomin was digested by pronase E and then the liberated glycopeptides were separated from non-glycopeptides by gel filtration chromatography on a Bio-Gel P-4 column. Three crude glycopeptides were obtained by continuing chromatography over anion-exchange resin (AG1-X2) in the buffer of 2% pyridine-acetic acid (pH 8.3) with a polygradient elution system. Through further purification by the gel filtration chromatography and HPLC, three major glycopeptides, GP1, GP2 and GP3 were obtained. Mainly by two-dimensional Nuclear Magnetic Resonance (NMR) including TOCSY, DQF-COSY, NOESY, HMQC and HMBC, their primary structures were analyzed as: Man1,3Man1,6(Man1,3)(Xyl1,2)Man1,4GlcNAc1,4GlcNAc1-(Gly-)Asn-Asn-Thr(GP1), Man1,6(Man1,3)(Xyl1,2)Man1,4GlcNAc1,4(Fuc1,3)GlcNAc1-Asn-Ala-Thr(GP2),Man1,6(Man1,3)Man1,6(Man1,2 Man1,3)Man1,4GlcNAc1,4GlcNAc1-(Ala-)Asn-Gly-Thr(GP3).     

Restriction fragment analysis of ‘null’ forms at the Gli-1 loci of bread and durum wheats

Summary Wheat accessions lacking some of the - and -gliadin components encoded by the Gli-1 loci on the short arm of chromosome 1D in bread wheat and chromosome 1A in durum wheat were studied by two-dimensional polyacrylamide gel electrophoresis and restriction fragment analysis. Digested genomic DNAs of normal and null forms were probed with a cDNA clone related to -/-gliadins and with a genomic clone encoding an LMW subunit of glutenin. The hybridisation patterns with the -/-gliadin probe were similar to those of cvs Chinese Spring and Langdon used as standards for bread and durum wheats, respectively, but several restriction fragments located on the 1D chromosome of bread wheat and the 1A chromosome of durum wheat were absent in the null forms. In addition, specific LMW glutenin fragments encoded by the same chromosomes were also absent in the null forms, suggesting that simultaneous deletions of blocks of genes for both -/-gliadins and LMW glutenins had occurred. Comparisons of the protein and RFLP patterns enabled some proteins to be mapped to specific restriction fragments.     

<Emphasis Type="Italic">Uncisudis posteropelvis</Emphasis>, a new species of barracudina (Aulopiformes: Paralepididae) from the western North Pacific Ocean

Six specimens (2 flexion larvae: 9.5–10.4mm in notochord length; 4 postflexion larvae: 12.3–18.2mm in standard length) collected from the western North Pacific are tentatively ascribed to the genus Uncisudis of the tribe Lestidiini of the subfamily Paralepidinae (Paralepididae) in sharing remarkably elongate and filamentous pelvic fin rays, their tips reaching the origin of the anal fin. They are described as Uncisudis posteropelvis sp. nov. in uniquely having the insertion of pelvic fins closer to the origin of anal fin than to the posterior end of dorsal fin base among lestidiine species. Addition to this character, the new species has remarkably elongate and filamentous dorsal fin rays, the short distance between anus and origin of anal fin (4.2–6.1% of standard length, SL), the posteriorly located pelvic fins (prepelvic length 69.4–71.5% SL), dorsal fin rays 10, anal fin rays 28–29, myomeres 41–42+38–40=80–81 (vertebrae 38+41=79), and peritoneal pigment spots 11–12. The occurrence of larvae differing in pigment pattern from the present new species suggests another undescribed species of Uncisudis in the western South Pacific.     

Systematics of Tanganyikan cichlid fishes (Teleostei: Perciformes)

The relationships among 53 genera of Tanganyikan cichlid fishes were analyzed based on internal and external morphological features. Comparison of the morphological cladistic tree with a previously proposed classification showed 5 of 12 tribes to be nonmonophyletic. Sixteen tribes were recognized, the changes in classification being that Trematocarini was treated as a junior synonym of Bathybatini; 5 new tribes were established for each of the following genera, Benthochromis, Boulengerochromis, Ctenochromis benthicola, Cyphotilapia, and Greenwoodochromis; Ctenochromis horei was transferred from Haplochromini to Tropheini; and Gnathochromis pfefferi was transferred from Limnochromini to Tropheini. The revised classification was supported by previously proposed molecular trees.     

The relation of proton motive force,adenylate energy charge and phosphorylation potential to the specific growth rate and efficiency of energy transduction inBacillus licheniformis under aerobic growth conditions

The magnitude of the proton motive force (p) and its constituents, the electrical () and chemical potential (-ZpH), were established for chemostat cultures of a protease-producing, relaxed (rel ^–) variant and a not protease-producing, stringent (rel ⁺) variant of an industrial strain ofBacillus licheniformis (respectively referred to as the A- and the B-type). For both types, an inverse relation of p with the specific growth rate was found. The calculated intracellular pH (pH_in) was not constant but inversely related to . This change in pH_in might be related to regulatory functions of metabolism but a regulatory role for pH_in itself could not be envisaged. Measurement of the adenylate energy charge (EC) showed a direct relation with for glucose-limited chemostat cultures; in nitrogen-limited chemostat cultures, the EC showed an approximately constant value at low and an increased value at higher . For both limitations, the ATP/ADP ratio was directly related to .The phosphorylation potential (G'p) was invariant with . From the values for G'p and p, a variable H⁺/ATP-stoichiometry was inferred: H⁺/ATP=1.83+0.52µ, so that at a given H⁺/O-ratio of four (4), the apparent P/O-ratio (inferred from regression analysis) showed a decline of 2.16 to 1.87 for =0 to _max (we discuss how more than half of this decline will be independent of any change in internal cell-volume). We propose that the constancy of G'p and the decrease in the efficiency of energy-conservation (P/O-value) with increasing are a way in which the cells try to cope with an apparent less than perfect coordination between anabolism and catabolism to keep up the highest possible with a minimum loss of growth-efficiency. Protease production in nitrogen-limited cultures as compared to glucose-limited cultures, and the difference between the A- and B-type, could not be explained by a different energy-status of the cells.Abbreviations CCCP carbonylcyanide-p-trichloromethoxyphenylhydrazone - DW dry weight of biomass - F Faraday's constant, 96.6 J/(mV × mol) - Fo chemostat outflow-rate (ml/h) - FCCP carbonylcyanide-p-trifluoromethoxyphenylhydrazone - G'p phosphorylation potential, the Gibbs energy change for ATP-synthesis from ADP and P_i - G'⁰p standard Gibbs energy change at specified conditions - H⁺/ATP number of protons translocated through - ATP synthase in synthesis of one ATP - H⁺/O protons translocated during transfer of 2 electrons from substrate to oxygen - specific growth rate (1/h) - _H+ transmembrane electrochemical proton potential, J/mol - M_b molar weight (147.6 g/mol) of bacteria with general cell formula C_6.0H_10.8O_3.0N_1.2 - pH_out,in extracellular, intracellular pH - P_i (intracellular) inorganic phosphate - p proton motive force, mV - pH transmembrane pH-difference - transmembrane electrical potential, mV - P/O number of ADP phosphorylated to ATP upon reduction of one O^2– to H₂O by two electrons transferred through the electron transfer chain - P/O (H⁺/O) × (H⁺/ATP)^–1 - P/O_F, P/O_N P/O with the two electrons donated by resp. (NADH + H⁺) and FADH - q specific rate of consumption or production (mol/g DW × h) - rel ⁺,rel ^– stringent, relaxed genotype - R universal gas constant, 8.36 J/(mol × degree) - T absolute temperature - TPMP⁺ triphenylmethylphosphonium ion - TPP⁺ tetraphenyl phosphonium ion - Y growth yield, g DW/mol - Z conversion constant=61.8 mV for 310 K (37 °C) - ZpH transmembrane proton potential or chemical potential, mV     

β-Ether cleavage of the lignin model compound 4-ethoxy-3-methoxyphenylglycerol-β-guaiacyl ether and derivatives by Phanerochaete chrysosporium

The white rot basidiomycete Phanerochaete chrysosporium metabolized 4-ethoxy-3-methoxyphenyl-glycerol--guaiacyl ether (V) in low nitrogen, stationary cultures under which conditions the ligninolytic enzyme system is expressed. 4-Ethoxy-3-methoxyphenylglycerol XIII, guaicol and 4-ethoxy-3-methoxybenzyl alcohol (II) were isolated as metabolic products. Exogenously added XIII was rapidly converted to 4-ethoxy-3-methoxybenzyl alcohol indicating that it is an intermediate in the metabolism of V. P. chrysosporium also metabolized 1-(4-ethoxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-3-hydroxypropane VI. The degradation pathway for this dimer also included initial -ether cleavage and -hydroxylation of the diol product 1-(4-ethoxy-3-methoxyphenyl) 2,3 dihydroxypropane (XI) to yield the triol XIII which was cleaved at the , bond to yield 4-ethoxy-3-methoxybenzyl alcohol. Finally P. chrysosporium also cleaved the dimer 1-(4-ethoxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)-1-hydroxypropane (VIII) at the -ether linkage yielding 1-(4-ethoxy-3-methoxyphenyl) 1,2 dihydroxypropane (IX) which was subsequently cleaved at the , bond to yield II. All of the results indicate that oxidative -ether cleavage is an important initial reaction in the metabolism of -aryl ether lignin substructure dimeric compounds. Metabolities were identified after comparison with chemically synthesized standards by gas liquid chromatography-mass spectrometry.Abbreviations GLC Gas liquid chromatography - TMSi trimethylsilyl - TLC thin layer chromatography     

Expectancy influence on self-reported experience during alpha feedback training

From a screening questionnaire, 12 subjects indicating some prior knowledge of alpha training (but no actual biofeedback training experience) and 12 subjects lacking such prior knowledge were selected for two 30-minute feedback sessions, one providing an opportunity to enhance and the other to suppress EEG alpha. Written self-reports of experiential state were independently rated by two judges on a five-point scale (Walsh, 1974) according to the degree to which they approximated alleged alpha vs. nonalpha experiences. These self-reports indicated that only the subjects expressing prior knowledge were able to differentiate between the enhancement and suppression sessions. A second study explored whether knowledgeable subjects (presumably those with positive expectancies) could make a similar differentiation when their expectancies regarding the type of feedback they would receive were manipulated. Twenty subjects received enhancement and 20 others received suppression feedback for four 40-minute sessions. Within each of these groups, 10 subjects were led to believe they enhanced alpha, and 10 were told they suppressed alpha. Half the subjects, therefore, believed they were attempting to change alpha in a direction opposite that of their actual task. Both actual and expected direction of alpha change significantly affected self-reports in the expected direction. Seemingly, situational expectancy alone was not sufficient to account for the actual feedback effects in the knowledgeable subjects. It is not entirely clear whether the alpha-related experiences reported by these knowledgeable subjects were responses to internal (i.e., physiologic state) or subtle external cues.