Showing papers by "University of Groningen published in 1982"
TL;DR: The emergence of spontaneous fetal motility during the first 20 weeks of gestation was studied longitudinally in 11 healthy nulliparae, using real-time ultrasound to study the onset and developmental course of spontaneously generated specific fetal movement patterns.
805 citations
TL;DR: The conclusion is reached that periods of coincidence occurred by chance and did not represent organized behavioural states in the human fetus.
769 citations
TL;DR: In this article, the tensile strength of poly(l-lactic) PLLA fibres with a high degree of molecular orientation and crystallinity were produced by hot drawing of the melt-spun and solution-sun fibres.
556 citations
TL;DR: In this paper, an item response theory is discussed which is based on purely ordinal assumptions about the probabilities that people respond positively to items and is considered as a natural generalization of both Guttman scaling and classical test theory.
Abstract: An item response theory is discussed which is based on purely ordinal assumptions about the probabilities that people respond positively to items. It is considered as a natural generalization of both Guttman scaling and classical test theory. A distinction is drawn between construction and evaluation of a test (or scale) on the one hand and the use of a test to measure and make decisions about persons' abilities on the other. Techniques to deal with each of these aspects are described and illustrated with examples.
382 citations
312 citations
TL;DR: Recent studies on mixed substrate utilization in both batch and continuous cultures have thrown light on the strategies of the control mechanisms that, in microbes, govern the utilization of the various substrates and indicated the possible significance of mixed substrates in microbial competition in nutrient-limited natural ecosystems.
Abstract: In natural and man-made environments microorganisms often grow in the presence of a diversity of functionally similar substrates. The pattern of utilization of these mixed substrates is generally dependent upon their concentration. When substrates are present in high (not growth-limiting) concentrations, sequential utilization and diauxic growth is often observed and the substrate that supports the highest growth rate is utilized preferentially from the mixture. When the substrate concentrations are growth-limiting, simultaneous utilization of the various compounds present in the mixture appears to be the general response. Recent studies on mixed substrate utilization in both batch and continuous cultures have thrown light on the strategies of the control mechanisms that, in microbes, govern the utilization of the various substrates. But perhaps more importantly these studies have indicated the possible significance of mixed substrate utilization in microbial competition in nutrient-limited natural ecosystems.
293 citations
TL;DR: Sixteen radiocarbon dates extending back to 70,000 years provide a chronology for the continuous continental pollen record of Grande Pile and indicate the cold period initiating the Middle Weichselian, which is marked by the disappearance of deciduous forests at this site.
Abstract: Sixteen radiocarbon dates extending back to 70,000 years provide a chronology for the continuous continental pollen record of Grande Pile. This record reflects climatic changes over the last 140,000 years in northeastern France. The cold period initiating the Middle Weichselian, dated previously at 55,000 years, is dated at 70,000 years before the present (B.P.) at Grande Pile. This event is marked by the disappearance of deciduous forests at this site. The Early Weichselian is placed before 70,000 years B.P. A correlation with the oxygen isotope stages from oceanic records is demonstrated until 70,000 years B.P. and attempted beyond.
273 citations
TL;DR: Only in a limited number of cases has it been adequately shown that the rectal route of administration gives plasma concentrations which are comparable to the oral route, but the influence of the formulation seems to be very critical.
Abstract: The human rectum represents a body cavity in which drugs can be easily introduced and retained and from which absorption is well possible. There are important therapeutic reasons why it is sometimes preferable to give a drug rectally rather than orally, e.g. in cases of nausea and vomiting. Drawbacks of rectal drug administration include the interruption of absorption by defaecation and lack of patient acceptability. The mechanism of drug absorption from the rectum is probably no different to that in the upper part of the gastrointestinal tract, despite the fact that the physiological circumstances (e.g. pH, fluid content) differ substantially. Absorption from aqueous and alcoholic solutions may occur very rapidly, which has proved to be of considerable therapeutic value in the rapid suppression of acute convulsive attacks by diazepam (e.g. in children), but absorption from suppositories is generally slower and very much dependent on the nature of the suppository base, the use of surfactants or other additives, particle size of the active ingredient, etc. There is some evidence that hepatic first-pass elimination of high clearance drugs is partially avoided after rectal administration, e.g. lignocaine. This can be explained by the rectal venous blood supply: the upper part is connected with the portal system, whereas the lower part is directly connected with the systemic circulation.
239 citations
TL;DR: Nine expert drivers operated an instrumented vehicle in tests over a highway at night after being treated with diazepam, a placebo, and nothing, and reacted to 10 milligrams of diazepAM with increased lateral position variability.
Abstract: Nine expert drivers operated an instrumented vehicle in tests over a highway at night after being treated with diazepam (5 and 10 milligrams), a placebo, and nothing They reacted to 10 milligrams of diazepam with increased lateral position variability Potentially dangerous impairment was inferred from the reactions of some subjects
201 citations
TL;DR: The first estimates of the extent of enzyme polymorphisms in populations of Drosophila pseudoobscura and humans based on electrophoresis of proteins were soon followed by many others, covering a wide range of animal and plant species, and showed that most species are highly polymorphic.
Abstract: In the late sixties the neo-Darwinian theory of evolution, hitherto generally accepted by biologists, was confronted with a new, revolutionary view: the theory of neutral or non-Darwinian evolution. In the neutralist view amino acid and nucleotide changes in the course of evolution are mainly due to random fixation of selectively neutral mutants (Kimura, 1968; King and Jukes, 1969). The approximately constant rate of evolution in terms of amino acid substitutions per site per year for various lineages, as claimed by neutralists, forms one of the main arguments for the neutralist theory. Enzyme polymorphisms in present-day populations are considered as a phase in molecular evolution (Kimura and Ohta, 1971; Kimura, 1977). The first estimates of the extent of enzyme polymorphisms in populations of Drosophila pseudoobscura (Lewontin and Hubby, 1966) and humans (Harris, 1966) based on electrophoresis of proteins were soon followed by many others, covering a wide range of animal and plant species. These surveys showed that most species are highly polymorphic [see reviews by Powell (1975), Nevo (1978), A. H. D. Brown (1979), and Hamrick et al. (1979)]. In the neutralist versus selectionist controversy the nature of these allozyme polymorphisms is disputed. Thw neutralist hypothesis states that the observed variation is mainly a product of mutation and drift of selectively neutral genes. The selectionist hypothesis claims that some from of balancing selection is resposible for the maintenance of allozyme polymorphisms.
193 citations
TL;DR: In this report, models for binding are presented which are based on the assumption that the binding is an energy-independent process and allow a proper calculation of the electrical potential when the binding of the probe to the different cellular components is known.
TL;DR: The presence on the mitochondrial DNA of N. crassa of a nucleotide sequence which potentially encodes another DCCD-binding protein is reported, suggesting a possible function of this gene and speculate on its evolutionary origin.
Abstract: The proton-translocating ATPases from mitochondria, chloroplasts and bacteria consist of ∼10 different polypeptide subunits1. The smallest subunit, a proteolipid of molecular weight ∼8,000, is present in a stoichiometric amount of six—these six polypeptides are thought to form a proton channel through the membrane2. The proteolipid is affected by the ATPase inhibitors oligomycin and dicyclohexylcarbodiimide (DCCD). As DCCD is covalently bound to it, the proteolipid is commonly referred to as the DCCD-binding protein. Because of the spatial arrangement of the proteolipids in the membrane, binding is probably restricted to one specific glutamic acid residue2,3. In the yeast Saccharomyces cerevisiae the DCCD-binding protein is encoded by the mitochondrial DNA and synthesized inside the mitochondria4, whereas in Neurospora crassa, another ascomycete, the gene for the DCCD-binding protein lies in the nucleus, and the protein is synthesized outside the mitochondria5. Here we report the presence on the mitochondrial DNA of N. crassa of a nucleotide sequence which potentially encodes another DCCD-binding protein. Although a translation product has not yet been found, we suggest a possible function of this gene and speculate on its evolutionary origin.
TL;DR: In this paper, the Ems-Dollard estuary was studied for light absorption and suspended matter measurements from 1976 to 1980, and it was demonstrated that the total irradiance available for phytoplankton depends to a small extent on the irradiance received during the submersion of the tidal flats.
TL;DR: In this paper, a modal approach utilizing known finite-dimensional algorithms for observer and stabilizer design is proposed for a large class of parabolic distributed systems, where the observer is constructed from observations taken from point or averaging sensors and the compensator is a feedback of this observer and can be a "distributed" or "boundary" implementation.
Abstract: A compensator design is proposed for a large class of parabolic distributed systems. Basically, it is a modal approach utilizing known finite-dimensional algorithms for observer and stabilizer design. The observer is constructed from observations taken from point or averaging sensors and the compensator is a feedback of this observer and can be a "distributed" or "boundary" implementation. Explicit sufficient conditions are given for the convergence of this scheme.
TL;DR: 3‐MT seems to be a much better indicator for decreased DA release than 3,4‐dihydroxyphenylacetic acid or homovanillic acid, and is concluded that a decreased release of DA is closely and rapidly reflected by decreased formation of 3‐MT.
Abstract: 3-Methoxytyramine (3-MT) was measured in the striata of rats killed by microwave radiation Apomorphine, gamma-butyrolactone (GBL), and reserpine decreased the 3-MT content A slight but transient increase in 3-MT was observed after haloperidol The turnover rate of 3-MT was unchanged 60 min after haloperidol treatment (+)-Amphetamine induced a pronounced rise in the 3-MT content, which was potentiated after combined treatment with haloperidol The increased 3-MT turnover rate that was observed after amphetamine treatment suggests that monoamine oxidase (MAO) inhibition is no explanation for the mechanism of interaction of this drug with dopamine (DA) metabolism The central stimulants amphonelic acid and nomifensine increased 3-MT levels; no substantial change was seen after benztropine, morphine, or oxotremorine It is concluded that a decreased release of DA is closely and rapidly reflected by decreased formation of 3-MT 3-MT seems to be a much better indicator for decreased DA release than 3,4-dihydroxyphenylacetic acid or homovanillic acid
TL;DR: In this article, Desulfobulbus propionicus came to the fore under iron-limited conditions in an ethanol-limited chemostat with excess sulfate inoculated with anaerobic intertidal freshwater sediment.
Abstract: Ethanol was rapidly degraded to mainly acetate in anaerobic freshwater sediment slurries. Propionate was produced in small amounts. Desulfovibrio species were the dominant bacteria among the ethanol-degrading organisms. The propionate-producing Desulfobulbus propionicus came to the fore under iron-limited conditions in an ethanol-limited chemostat with excess sulfate inoculated with anaerobic intertidal freshwater sediment. In the absence of sulfate, ethanol was fermented by D. propionicus Lindhorst to propionate and acetate in a molar ratio of 2.0.l-Propanol was intermediately produced during the fermentation of ethanol. In the presence of H2 and CO2, ethanol was quantitatively converted to propionate. H2-plus sulfate-grown cells of D. propionicus Lindhorst were able to oxidize l-propanol and l-butanol to propionate and butyrate respectively with the concomitant reduction of acetate plus CO2 to propionate. Growth was also observed on acetate alone in the presence of H2 and CO2
D. propionicus was able to grow mixotrophically on H2 plus an organic compound. Finally, a brief discussion has been given of the ecological niche of D. propionicus in anaerobic freshwater sediments.
TL;DR: The kinetics of diatom growth on a mudflat in the Ems-Dollard estuary were analysed from field observations and experiments carried out during a spring bloom, suggesting a per day balanced budget of carbon-limited photosynthesis and respiratory or excretory losses.
Abstract: The kinetics of diatom growth on a mudflat in the Ems-Dollard estuary were analysed from field observations and experiments carried out during a spring bloom. Low-density natural populations of epipelic diatoms showed an exponential increase in cell number with an apparent cell division rate of 0·3 day−1. Similar division rates were measured in natural populations, incubated on their sediment in the laboratory and in unialgal cultures of dominant diatom species grown on interstitial water. The vertical migration of diatom cells in ‘dark’ millimeters deep sediment layers apparently did not decrease the mean cell division rate in the populations. The diatom populations on the mudflat reached densities of 1–×106 cells cm−2; these densities are comparable to peak values of chlorophyll a concentrations of 100–400 mg m−1 of sediment, as reported for microphytobenthos in the literature. In dense natural populations and in dense unialgal cultures similar patterns were found in the accumulation of biomass (as chlorophyll a or cell numbers), in the limitation of productivity (as mg O2 m−2 h−1) and in the decrease of cell division rate. The diffusion of inorganic carbon and oxygen between the diatom film and the overlying water limited the productivity of dense diatom populations to ca. 500 mg O2 h−1 or less depending on the external concentrations of inorganic carbon and oxygen, and the flow rate of the water. Correspondingly, the rate of cell production in dense culture reached an upper level and this resulted in linear growth curves. The rate of this linear growth was affected also by the length of the daily light period. At the highest densities of cultures and natural populations the population growth drops to zero, suggesting a per day balanced budget of carbon-limited photosynthesis and respiratory or excretory losses. Self-shading had no effect on the division rate in dense cultures. The supply of nutrients (as P, N or Si) was not a critical factor to the growth rate of natural populations on the nutriet-rich mudflat, nor to cultures under the conditions tested.
TL;DR: Comparison of 11-d light-grown pea plants with 4-dLight-grown seedlings did not reveal additional translatable RNA sequences, indicating that the major morphogenetic changes that occur after 4 d are not accompanied by significant changes in the pattern of abundant RNA sequences.
Abstract: The diversity of abundant mRNA sequences in various parts of 4-d etiolated pea seedlings (Pisum sativum L var Rondo CB) was compared by a cell-free translation of the mRNAs in the presence of [35S]methionine and by an analysis of the products by two-dimensional electrofocussing/ electrophoresis (2D separation) The various parts of the seedlings were also examined for the pattern of protein synthesis in vivo Proteins were labeled by injection of [35S]methionine into the cotyledons, followed by 2D separation of the products Over 95% of the abundant mRNA sequences and newly synthesized abundant polypeptides were shared by all parts of etiolated seedlings, including the cotyledons However, a few distinct differences were observed when comparing mRNAs of roots and shoots; the most prominent among these were a group of six abundant mRNA sequences found exclusively in shoots Only about 30% of the polypeptides synthesized on isolated RNA could be traced in equivalent positions on the gels as the polypeptides synthesized in vivo Analysis of total RNA from light-grown pea seedlings showed the appearance of some twenty-five translation products not found with total RNA from etiolated seedlings, while about nine other translation products disappeared At least ten of the light-induced RNA sequences were also present after growth in low-intensity red light (λ>600 nm) and are therefore thought to be controlled by the phytochrome system Comparison of 11-d light-grown pea plants with 4-d light-grown seedlings did not reveal additional translatable RNA sequences, indicating that the major morphogenetic changes that occur after 4 d are not accompanied by significant changes in the pattern of abundant RNA sequences
01 Jan 1982
TL;DR: To be of full functional significance for the organism, circadian rhythms have to be synchronized to the 24-h day and can be entrained to periods deviating from 24 h only within certain limits.
Abstract: To be of full functional significance for the organism, circadian rhythms have to be synchronized to the 24-h day. This is done by response to periodic signals from the environment, the Zeitgebers (Pittendrigh 1981). The entrained state is characterized by a stable phase angle difference ψ between rhythm and Zeitgeber; sign and amount of ψ depend on the period τ of the rhythm (as measured in constant conditions) and on the period T of the Zeitgeber. Furthermore, circadian systems can be entrained to periods deviating from 24 h only within certain limits (Aschoff and Pohl 1978).
TL;DR: The activity of the alternative respiratory pathway in the Rootago lanceolata is strongly affected by a sudden temperature change in the root environment, described by ‘the energy overflow model'.
Abstract: The long and short term metabolic effects of a shift in root temperature was investigated in Plantago lanceolata L. with special reference to the role of the cyanide resistant alternative pathway in root respiration. After a 10-day period of growth at a 13°C root temperature, a decrease in root as well as shoot growth was observed, compared to control plants grown continuously at 21°C. Apart from an increase in shoot soluble and insoluble sugar level, no changes in metabolism were found, neither in root respiration, shoot photosynthesis, nor in root sugar and plant protein level.
Decreasing the root temperature from 21 to 13°C gave several clear short term changes in metabolism. Within one hour a decrease in cytochrome chain activity of the roots was found together with an increase in activity of the alternative chain. After 24 h a recovery to the initial level of both chains was observed. An increase in root temperature from 13 to 21°C gave an immediate increase in activity of both respiratory chains that was still present 24 h after the switch.
It is concluded that the activity of the alternative respiratory pathway in the root is strongly affected by a sudden temperature change in the root environment. This pathway acts in a way which is described by ‘the energy overflow model'. The presence of the alternative electron transport pathway should be taken into account in determinations of the respiratory Q10. Moreover, the length of time between the temperature change and respiration measurements is an important factor.
TL;DR: The model presented here explains the known inhibiting effects of buffers and high pH on photosynlhetic HCO3− utilization and concludes that the acidification results from the activity of light‐dependent H+ pumps.
Abstract: Photosynthetic utilization of HCO, in leaves of Poiamogeton and Elodea occurs at the lower leaf side, with subsequent OH∼ release at the upper side. It is accompanied by transport of cations, in the present experiment K +, across the leaf. The resulting pH and K+ concentration changes near the leaf surface were recorded with miniature electrodes. From the pH and K+ concentration the concentrations of the different inorganic carbon species were calculated and compared with photosynthetic O, production. HCO−3 utilization is accompanied by a drastic increase in the free CO2 concentration near the lower epidermis. Experiments with CO2− and HCO3−free solutions showed an oscillating acidification near the lower epidermis and alkalinization near the upper epidermis. It is concluded that the acidification results from the activity of light‐dependent H+ pumps. The finding that an increase in pH at the upper side always coincided with a decrease at the lower in these experiments shows that the H+ pumps and the OH− extruding mechanism are coupled although occurring in different cell layers. Previously we have suggested that the first step in the process of photosynthetic HCO3− utilization is external conversion of HCO3−” by acidification caused by light‐dependent H+ pumps. The present results strongly support this hypothesis. Two possible pathways for the accompanying K + transport are discussed. The model presented here explains the known inhibiting effects of buffers and high pH on photosynlhetic HCO3− utilization.
TL;DR: It is concluded that mosaic non-equilibrium thermodynamics will be a powerful theoretical tool especially in future experimental analyses of the metabolic basis for microbial growth characteristics and growth regulation.
TL;DR: In this article, the authors suggest that α-clustering may play an important role in the structure of heavy nuclei and propose a phenomenological model for treating it, which is based on α-Clustering.
TL;DR: In this article, a survey and interpretation of perturbed angular correlations (PAC) and perturbation angular distribution (PAD) data for seven fcc metals (Ag, Al, Au, Cu, Ni, Pd, Pt) using the same probe is presented.
Abstract: In the past six years perturbed angular correlations (PAC) and perturbed angular distribution (PAD) of $\ensuremath{\gamma}$ rays have been widely applied to study the migration, trapping, and clustering of lattice defects in metals. Essential features of these experiments are distinctive precessional signals arising in the nuclear hyperfine interaction. These signals serve as convenient labels for specific lattice defects bound to $\ensuremath{\gamma}$-ray-emitting probe atoms, and under favorable circumstances provide information on the lattice symmetry of the defects. Because we believe that the maximum information is obtained from such experiments if systematic comparisons are made between similar metals, we describe here our survey and interpretation of PAC and PAD data for seven fcc metals (Ag, Al, Au, Cu, Ni, Pd, Pt) using $^{111}\mathrm{Cd}$ probe. We consider defect production by irradiation, quenching, and ion-implantation, and note that the same defect types recur in all three methods. We include a total of 19 distinctive states in our discussion, and through a series of independent, comparative observations we argue that these states involve vacancy defects bound to the $^{111}\mathrm{Cd}$ probe. On the basis of the observed frequencies, annealing behavior, and electric-field-gradient symmetry we divide vacancy states into four classes. For three of these classes structural assignments can be made. These include the nearest-neighbor monovacancy observed in five metals, divacancies or faulted loops in the {111} plane observed in six metals, and a tetrahedral cluster seen only in Ni. For the nearest-neighbor monovacancy the data permit estimation of migration enthalpies. For the monovacancy the data also permit an interpretation of the observed electric field gradients. Though some of the observed states remain with undetermined structure, we believe our comparative analysis provides an excellent foundation for further detailed study of small vacancy clusters under a variety of metallurgical conditions.
01 Jan 1982
TL;DR: In focussing on how circadian rhythms contribute to survival, it is well to consider them, first, as part of a spectrum of rhythms and to evaluate their possible intrinsic function regardless of the environmental day-night cycle.
Abstract: The significance of biological rhythms can be discussed under at least two aspects. They serve, on the one hand, to attain an optimal temporal arrangement of animal behaviour within the cycles of the environment, as in the four “circa-clocks” (Aschoff 1981). On the other hand, this external adaptation results in internal temporal order which in itself may have selective value. In addition, there are many rhythmic processes within the organism, not related to any environmental periodicity, which in various ways contribute to the maintenance of functional integrity of the internal milieu (Aschoff and Wever 1961). In focussing on how circadian rhythms contribute to survival, we do well to consider them, first, as part of a spectrum of rhythms and to evaluate their possible intrinsic function regardless of the environmental day-night cycle. We then will proceed to a discussion of possible benefits to be derived from the adjustment to the periodic environment.
TL;DR: It is suggested that a reduced beta-adrenergic function is not an intrinsic component of allergic bronchial asthma but is rather the consequence of an active disease state, and that alterations distal to the receptor may play an important role in the observed decrease in beta- adrenergic responsiveness.
Abstract: Beta-adrenergic receptor characteristics and adenylate cyclase responses to different stimuli were measured in lymphocyte membrane preparations of six normal control subjects and five allergic asthmatic patients with mild airways disease and increased bronchial reactivity to histamine and acetylcholine. The determinations were performed just before and 24 hr after inhalation challenge with house-dust mite antigen to investigate the influence of an allergen-induced asthmatic attack on the beta-adrenergic receptor system. Before the house-dust mite challenge, the lymphocyte membranes of the patients showed a normal receptor density, dissociation constant for (-)3H-dihydroalprenolol, and adenylate cyclase response to isoproterenol, guanyl-5'-yl-imidodiphosphate, (GppNHp) and NaF. After the allergen-induced asthmatic reaction, however, the beta-adrenergic receptor number in the patients was significantly reduced by 21%, while the basal adenylate cyclase activity and isoproterenol-, GppNHp-, and NaF-induced cyclic AMP responses were simultaneously reduced by about 40%. The allergen challenge had no significant effect on the lymphocyte membranes of the control subjects. These results suggest (1) that a reduced beta-adrenergic function is not an intrinsic component of allergic bronchial asthma but is rather the consequence of an active disease state, and (2) that next to changes in beta-adrenergic receptor number, alterations distal to the receptor may play an important role in the observed decrease in beta-adrenergic responsiveness.
TL;DR: It was found that prescribing rationality is a physician characteristic and younger General Practitioners prescribe in a more rational way than their older colleagues and this is partly reflected in the patterns of obtaining information.
TL;DR: Competition experiments carried out between specialized and versatile Thiobacilli strongly indicate that the ecological advantage of the versatile thiobACilli may lie not so much in their short-term flexibility, but rather in their ability to grow mixotrophically.
Abstract: Recent studies on the ecophysiology of the obligate chemolithotroph Thiobacillus neapolitanus have given better insight into its specialization for an autotrophic mode of life. This appears not only from its high constitutive levels of autotrophic enzymes, but also from its possession of carboxysomes, which seem to be specialized organelles for CO2 fixation and concentrating reducing power. At the same time, these organisms are metabolically versatile with respect to nitrogen assimilation pathways, and during starvation are able to utilize endogenous resources such as polyglucose for carbon and energy. Studies on the facultative chemolithotrophs such as Thiobacillus novellus and Thiobacillus A2 have shown that they can grow mixotrophically on mixtures of inorganic and organic substrates, i.e. they can utilize these compounds simultaneously provided that they are growth limiting. Thiobacillus A2 displays a remarkable flexibility not only with respect to the organic substrates that it can utilize but, for example, also in the choice of various pathways for glucose metabolism. Competition experiments carried out between specialized and versatile thiobacilli strongly indicate that the ecological advantage of the versatile thiobacilli may lie not so much in their short-term flexibility, but rather in their ability to grow mixotrophically. Studies on most heterotrophic chemolithotrophs are still in their infancy. Promising progress has been made in the study of the physiology of Beggiatoa species. Renewed interest in the sulphur-oxidizing bacteria stems from recent findings about their role in food chains, and their possible application in industry.
TL;DR: In this paper, an algebraic approach to tri-and poly-atomic molecules is presented and applied to the study of linear triatomic molecules, and it is suggested that these techniques may be useful in the description of complex molecular rotation-vibration spectra.
TL;DR: It is concluded that in the rat striatum about 80% of homovanillic acid is formed from 3,4‐dihydroxyphenylacetic acid and 20% from 3‐MT.
Abstract: A highly sensitive method for the determination of 3-methoxytyramine (3-MT) in nervous tissue is described. The method is based on a rapidly performed isolation of 3-MT on small columns of Sephadex G 10, followed by reverse-phase high-performance liquid chromatography in conjunction with a rotating disk electrochemical detector. The detection limit of the assay (0.5–1 pmol/tissue sample) is about 10% of control value for microwave-killed rats. 3-MT as well as dopamine could be quantified in the same chromatographic run. Inhibition of catechol-O-methyl transferase with tropolone resulted in an exponential decline of 3-MT. From this exponential decline a turnover rate for 3-MT of 1.9 nmol/g/h was calculated. In the same group of rats the turnover rate of homovanillic acid was 9.1 nmol/g/h. From these data it is concluded that in the rat striatum about 80% of homovanillic acid is formed from 3,4-dihydroxyphenylacetic acid and 20% from 3-MT.