Norepinephrine Metabolism in Humans Studied by Deuterium Labelling: Turnover of 4–Hydroxy-3–methoxyphenylglycol

Abstract: D, L(±)-4-Hydroxy-3-methoxyphenylglycol (HMPG) labelled with three deuterium atoms was used to study turnover of plasma free HMPG following an intravenous injection. Ten healthy men were given a pulse dose of either 4.3 μmol or 2.2 μmol of labelled HMPG ([²H₃]HMPG piperazine salt). Plasma and urine levels of both endogenous and labelled HMPG were subsequently followed by gas chromatography-mass spectrometry with selected ion detection. Kinetic calculations based upon a single-compartment model were consistent with a monoexponential elimination of plasma free HMPG. The half-life of HMPG was 0.46 and 0.78 h (mean values in the two dose groups). The HMPG production rate was 2.01 and 2.35 μmol/hour, and the urinary excretion rate of HMPG (free and conjugated) was 0.48 and 0.47 μmol/h. The endogenous plasma level of free HMPG was 25 and 33 nmol/L. The results show that HMPG turns over rapidly and that HMPG is further metabolized extensively. About one-fourth of the HMPG produced is excreted in urine as free and conjugated HMPG.     

Caprolactam,a light-promoted growth inhibitor in sunflower seedlings

A neutral growth inhibitor, isolated from methanolic extracts of sunflower seedlings, was characterized by spectral data as caprolactam. Light-grown se     

Foraminifera from the Silberberg Formation («Lower Oligocene») at Silberberg,near Helmstedt (Germany)

From the Silberberg Quarry, type locality of the Silberberg Formation (Martini &Ritzkowski 1968), some planktonic foraminifera are described:Globigerina officinalis Subbotina, Globigerina ouachitaensisHowe &Wallace,G. praebulloides leroyi Blow &Banner, G.praebulloides occlusa Blow &Banner which taxa are here suggested to form intergrading morphotypes within the range of variation of a population dominated byG. officinalis. In addition,G. cf.danvillensis Howe &Wallace is found. The planktonic fauna, together with some elements in the benthonic fauna, suggests a possible correlation with the Danville Landing Member of the Jackson Formation, Louisiana, traditionally ascribed to the Upper Eocene. There is some similarity with European Uppermost Eocene — Lower Oligocene faunas described by various authors. The Silberberg Formation was suggested to be a Neostratotype for the Latdorfian Stage of the Lower Oligocene byMartini &Ritzkowski (1968). It is suggested that the Silberberg Formation may well be coeval with the Upper Priabonian as proposed byCita 1969.     

Feedback regulation of the alpha electroencephalogram activity through control of the internal and external parameters

Summary Experiments with feedback stimulation triggered from the subject's electroencephalogram result in changing the sequential time series of intervals of occipital alpha and intervals of little or no alpha EEG activity. The rate of recurrence of alpha and no-alpha EEG can be changed by regulating the external feedback stimuli or by asking the subject to change his internal state. Four different paradigms were investigated and the results interpreted in terms of the hypothesis that oculomotor functions regulate the occurrence and nonoccurrence of alpha.This work was supported by NIGMS Grants 5 PO1 GM 14940-04 and GM 15006-03.Most of this research was conducted at the Perception Laboratory, Veterans' Administration Hospital, Bedford, Massachusetts, with the cooperation of Dr. Thomas B. Mulholland.     

Die Schätzung der Varianzkomponenten beim Fixwertmodell der Varianzanalyse

Zusammenfassung Die Schätzung der Varianzkomponenten bei Versuchen mit festen Variabilitätsursachen, z. B. bei der Prüfung von Sorten, Behandlungen usw., ist nur dann sinnvoll, wenn die Varianzkomponenten so definiert sind, daß ihre Summe der Gesamtvarianz gleich ist, d. h. daß sie sich additiv verhalten. Will man die so definierten Varianzkomponenten erwartungstreu schätzen, muß man die Überhöhung der mittleren Quadrate, die durch Division mit Freiheitsgraden statt mit der Gruppenzahl entstanden ist, wieder korrigieren. Diese Korrektion entfällt bei der Schätzung der Varianz von Zufallswirkungen.Die Erwartungswerte der mittleren Quadrate der üblichen varianzanalytischen Zerlegung und die erwartungstreuen Schätzungen der additiv definierten Varianzkomponenten werden am Beispiel eines Versuches mit zwei konstanten Variabilitätsursachen und einer Zufallseinwirkung dargelegt.

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Estimating variance components in a fixed model of variance analysis

Summary The partition of a variance into components in experiments with fixed effects, i.e. experiments with varieties, treatment etc., is meaningful only if components are defined as additive parts of a whole. This also demands that the sum of the components of variance be equal to the total variance. Such additivity of the components of variance is achieved by appropriate definitions of the components of variance. Unbiassed estimates of the additively defined components of variance are obtained by a simple correction which eliminates the influence of degrees of freedom on the calculation of mean squares. This correction is not needed for the estimation of variances of random effects.The expected values of mean squares for the partition of variance and formulas for unbiassed estimates of additively defined components of variance are demonstrated in an experiment with two fixed effects and one random effect.

     

Why do males of the dance flyEmpis borealis refuse to mate? The importance of female age and size

Empis borealisfemales form swarms, and males carrying a nuptial gift come to swarms to mate. Males either mated with one of the females (accepted swarms) or left swarms without mating (refused swarms). Males mated with the younger (low wing-wear) and relatively larger females in accepted swarms. They seemed to be able to judge the relative size of the females but to ignore their absolute size. Visiting males stayed shorter in accepted swarms as female size variation increased. This probably reflects their greater ease in choosing a mate among females of relatively different sizes. Females in accepted swarms tended to be larger and to have less worn wings than females in rejected swarms.     

Food limitation and social regulation in a red fox population

This study evaluates a conceptual model on functional and numerical response to short-term fluctuating vole populations of a red fox ( Vulpes vulpes L.) population in south-central Sweden. The model assumes that this particular population is located in between socially regulated stable populations to the south and direct food-limited populations to the north. The model predicts: (1) food availability as the primary factor for limiting fox numbers, causing reduced rates of reproduction and survival during years of low vole densities, and (2) density-dependent regulation during years of increasing and high vole densities resulting in increased group sizes within territories of fixed dimensions. During 1973–1980 data were obtained from 1216 fox scats, 874 fox carcasses, 63 tagged foxes, nine radio-collared females and from yearly den counts in an area of 130 km², Eight predictions of the model were tested. These concerned the occurrence of small rodents in fox diet, fluctuations in the density of foxes, variations in the number of fox litters, the effect on reproduction of providing supplemental food during January–May, the proportion of vixens bearing a litter different years, dispersal of young males relative to that of young females throughout the vole cycle, and variations in mortality rates of young males and females. All tests were in favour of the conceptual model, and contradictory to alternative models.