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  • General Chemistry  (17)
  • Node of Ranvier  (4)
  • Phenylketonuria  (4)
  • Ethanol  (3)
  • Key words Phenylketonuria  (3)
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Keywords
  • 1
    ISSN: 0003-2670
    Keywords: Ethanol ; Fermentation ; Flow system ; Fluorimetry ; Foods ; Fruit juices ; Glucose ; Process analysis ; Pullulan: Sucrose ; Spectrophotometry
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0003-2670
    Keywords: Ethanol ; Fermentation ; Flow system ; Fluorimetry ; Foods ; Fruit juices ; Glucose ; Process analysis ; Pullulan Sucrose ; Spectrophotometry
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Zeitschrift für Lebensmittel-Untersuchung und -Forschung 205 (1997), S. 158-164 
    ISSN: 1431-4630
    Keywords: Key words Adulteration ; Carbon-13 ; Citric acid ; Ethanol ; Malic acid ; Tartaric acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract  The δ13C-values of organic acids and their correlations to those of the sugar and ethanol, respectively, from 57 EU data bank wines of the Rheinpfalz area (years 1991 – 1993) and from some of their corresponding musts have been determined. In addition to the well established difference between fermented sugar and ethanol (Δδ13C = –1.7±0.2‰), a new constant correlation was found in wine for ethanol and citric acid (Δδ13C = +2.4±0.4‰). From this result a fixed δ-value difference for citric acid in wine to the fermented sugar of +0.7±0.6‰ can be deduced. The δ13C-values of L-malic acid and L-tartaric acid in must were not altered by the alcoholic fermentation; they should therefore directly provide access to the δ13C-value of the natural sugar in must. However, in non-adulterated wines the expected δ13C-value differences between these acids and ethanol showed unsatisfactory correlation coefficients. For L-malate this is attributed to the secondary (partial) degradation of this acid by the malolactic fermentation; a corresponding correction is envisaged in order to make L-malate available as an internal standard. As a reason for the unsatisfactory correlation between L-tartaric acid and ethanol, it is supposed that the time of its maximum biosynthesis period does not coincide with that of glucose in the grape ripening period.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 349 (1974), S. 133-148 
    ISSN: 1432-2013
    Keywords: Node of Ranvier ; Sodium Permeability ; Aconitine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of aconitine (10−5–10−6 g/ml) on membrane potentials and membrane currents of myelinated nerve fibres of Xenopus laevis was investigated. The following observations were made: a) Current clamp conditions: Slow depolarization (10–15 mV), decrease of amplitude and maximum rate of rise of action potential, finally inexcitability. With inward current pulses ‘hyperpolarizing responses’ could be elicited at membrane potentials more negative than the resting potential (E r ). Neither spontaneous activity nor repetitive responses to electrical stimuli were observed. No effects of aconitine were found in Na-free solutions or in the presence of tetrodotoxin. b) Voltage clamp conditions: Development of steady inward current at normal resting potential due to formation of a non-inactivating sodium permeability; heavily poisoned nodes therefore exhibit an N-shaped steady-state current voltage relation with negative slope at membrane potentials more negative thanE r . These non-inactivating sodium channels open more slowly than normal sodium channels, and can only be closed by hyperpolarizing the membrane by about 50 mV. The majority of sodium channels have almost normalτ m; theirm ∞ andh ∞-V relations are shifted by 10–15 mV towardsE r . It is concluded that these changes of the sodium permeability account for the changes of electrical activity observed after treatment with aconitine.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1076
    Keywords: CNS development ; Dietary treatment ; EEG ; IQ ; Phenylketonuria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In 34 children with phenylketonuria (PKU) treated early the prognostic value of the age on institution of the diet (within the first 3 months of life) and of the quality of dietary treatment was determined in two different ways: 1) following intelligence closely (IQ) and (2) evaluating the EEG development up to their 12th (n=34) and 15th (n=18) years of life as appropriate. In general, IQ scores were found to be normal from the 4th–15th years of life. In our group of patients there was no effect on the IQ of the timing of diet onset. Children with “strict” dietary control showed a significantly higher IQ than those with “loose” control. One hundred and fifty-four EEGs (10/20 system, awake with eyes closed) were recorded at intervals of 2 years and conventionally evaluated. The development of alpha-activity was found to be normal. Beta-activity was enhanced. Abnormal EEG findings like general slowing and generalized paroxysmal activity (GPA) with or without spikes were more frequent in children with PKU than in controls, with the exception of focal abnormalities. EEG abnormalities increased with advancing age independently of IQ development and showed no relation to either the age at the onset nor the quality of dietary treatment.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1076
    Keywords: Phenylketonuria ; Biopterin ; Phosphate-eliminating enzyme ; 6-Pyruvoyl tetrahydropterin synthase ; Amniotic fluid ; Erythrocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Amniocentesis was performed at 19 weeks gestation in a mother who had previously delivered a boy with “dihydrobiopterin synthetase” (DHBS) deficiency. The amniotic fluid contained neopterin in high (136 nmol/l) and biopterin in very low concentrations (1.8 nmol/l). The activity of the phosphate-eliminating enzyme (PEE, also called 6-pyruvoyl tetrahydropterin synthase, substrate: 7,8-dihydroneoptein triphosphate) which is present in liver and erythrocytes and defective in DHBS deficiency, was measured in the erythrocytes of the family members. The fetal sample showed only 2% of the activity of healthy adult controls and was comparable with that of the affected sibling. Obligate heterozygotes had activities around 20% of the controls. Two fetal control samples showed even higher activities than adult erythrocytes. Sepiapterin reductase activities were normal in all cases. At autopsy, PEE deficiency was confirmed in the liver of the fetus. We concluded that DHBS deficiency (and most probably also GTP cyclohydrolase I deficiency) can be diagnosed by metabolite measurements in amniotic fluid. PEE activity is measurable in erythrocytes, although the assay needs to be improved. Since maternal tetrahydrobiopterin does not cross the placenta, treatment of a tetrahydrobiopterin-deficient fetus with tetrahydrobiopterin in utero is not possible.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1076
    Keywords: Key words Phenylketonuria ; Phenylalanine ; Magnetic resonance ; imaging ; Evoked potentials ; Myelination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract White matter abnormalities on MRI have been observed in phenylketonuria (PKU) patients with late onset neurological symptoms as well as in neurologically inconspicious patients. We investigated 14 early treated adolescents at an age between 12 and 17 years (mean age 14.3 years) with classical PKU as well as one retarded patient with atypical PKU by cranial MRI with spinecho T1-, T2- and proton density sequences. Clinical examination was normal. Visual evoked potential (VEP) examination showed a prolonged latency of peak P100 (mean 122.6 ms; control mean 115.9) and IQ testing showed a mean IQ of 101.1. To investigate the influence of plasma phenylalanine (Phe) levels three approaches were used: Phe was determined for the day of MRI, for a period of 6 months prior to MRI and for lifetime up to 12 years. MRI scans revealed areas of abnormally increased signal intensity on T2-weighted and proton density images in 12 (86%) patients, preferably involving the parieto-occipital lobes. MRI of the patient with atypical PKU was normal. MRI findings correlated most strongly to long-term dietary control up to 12 years. We found no correlation with the other parameters of biochemical control, IQ or VEP latency. The nature and prognosis of MRI abnormalities in neurologically normal PKU patients remain unclear although abnormalities in VEPs which were not associated with the degree of MRI abnormalities in our sample indicate a disturbance in myelination along the visual pathways.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 157 (1998), S. 824-830 
    ISSN: 1432-1076
    Keywords: Key words Intelligence ; Neurology ; Neuropsychology ; Phenylketonuria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Due to the observation of severe neurological symptoms in single patients as well as brain imaging, neuropsychological and neurophysiological abnormalities, the long-term prognosis of treated phenylketonuria is still under discussion. We investigated the neurological outcome of 57 (24 male, 33 female) patients with phenylketonuria (diet onset 〈3 months) at a mean age of 23.6 (17–33) years in comparison to control subjects. Methods used were a clinical-neurological examination, tests for fine motor abilities, IQ test (WAIS-R), a neuropsychological attention task and MRI (30 patients only). Tremor was increased in the patients (28%) compared to controls (15%). Fine motor abilities were significantly reduced in three areas: hand-wrist steadiness, finger-hand dexterity and hand-wrist speed. Tremor as well as reduced fine motor skills were not associated with treatment-related variables, e.g. diet onset, strictness of biochemical control or amount of MRI white matter change. IQ was lower in patients (mean 97.6) compared to matched control subjects (mean 105.5). IQ at 12 years was correlated with biochemical control from birth up to the age of 12 and remained stable up to adult age, independent of biochemical control after 12 years of age. In contrast to the other outcome parameters, the performance in a neuropsychological attention task was influenced by the concurrent plasma phenylalanine concentration. Specific late-onset neurological impairment was not identified in this sample of early-treated adults with phenylketonuria. Conclusion Careful neurological investigation revealed subtle symptoms of brain damage even after early-initiated treatment in adult patients with phenylketonuria. At present it cannot be excluded that further neurological deterioration could emerge later in life. Thus, patients with phenylketonuria – either on or off diet – should be monitored throughout life.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1076
    Keywords: Key words Phenylketonuria ; Genotype ; Treatment ; IQ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The interdependence of the predicted in vitro residual enzyme activity (PRA), as deduced from the complete genotypes of 64 hyperphenylalaninaemic patients, and parameters for diagnosis of hyperphenylalaninaemic disorders, the fluctuation of the phyenlylalanine (Phe) values during treatment, long-term dietary control during treatment, and a parameter for the outcome of therapy (IQ) was investigated by correlation analysis. A highly significant correlation was found between the PRA and diagnostic parameters, as well as the fluctuation of the Phe values during treatment. Significant correlations were also observed between the parameter describing the fluctuation of the Phe values and the IQ, as well as between the quality of dietary control and IQ. The PRA is a valuable tool for the differential diagnosis of hyperphenylalaninaemic disorders and for the prediction of one aspect of the course of the disease which is related to the intellectual outcome of therapy. The quality of dietary control was independent of the genotype, indicating that the outcome of therapy can be successfully manipulated in spite of the genetic make-up.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of pediatrics 155 (1996), S. S97 
    ISSN: 1432-1076
    Keywords: Key words Phenylketonuria ; Intelligence ; Education ; Professional career ; Phenylalanine ; control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The intellectual status and professional careers of 51 young adults with phenylketonuria whose treatment started before 3 months of age are described. Their mean IQ was 97 (SD = 16). Of the IQs, 4% were more than 2 SD below the norm. The distribution of types of schooling of the patients was comparable to that in the German population. The professional careers of nearly all the patients were according to their educational level. Within the sample the outcome was significantly correlated with phenylalanine (Phe) control, even when the patients’ social background was statistically taken into account. The main influence of Phe on intelligence seems to occur during the first decade of life since IQ data remain stable even after Phe levels increased during adolescence.
    Type of Medium: Electronic Resource
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