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  • Polymer and Materials Science  (23)
  • Phenylketonuria  (4)
  • Key words Phenylketonuria  (3)
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  • 1
    Digitale Medien
    Digitale Medien
    Long-term development of intelligence (IQ) and EEG in 34 children with phenylketonuria treated early (1988)
    Springer
    European journal of pediatrics 147 (1988), S. 361-367 
    Details
    ISSN: 1432-1076
    Schlagwort(e): CNS development ; Dietary treatment ; EEG ; IQ ; Phenylketonuria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00496411
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  • 2
    Digitale Medien
    Digitale Medien
    Prenatal diagnosis of “dihydrobiopterin synthetase” deficiency, a variant form of phenylketonuria (1986)
    Springer
    European journal of pediatrics 145 (1986), S. 176-178 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Phenylketonuria ; Biopterin ; Phosphate-eliminating enzyme ; 6-Pyruvoyl tetrahydropterin synthase ; Amniotic fluid ; Erythrocytes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00446058
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  • 3
    Digitale Medien
    Digitale Medien
    Magnetic resonance imaging of the brain in adolescents with phenyketonuria and in one case of 6-pyruvoyl tetrahydropteridine synthase deficiency (1996)
    Springer
    European journal of pediatrics 155 (1996), S. S69 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Phenylketonuria ; Phenylalanine ; Magnetic resonance ; imaging ; Evoked potentials ; Myelination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00014255
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  • 4
    Digitale Medien
    Digitale Medien
    Neurological outcome in adult patients with early-treated phenylketonuria (1998)
    Springer
    European journal of pediatrics 157 (1998), S. 824-830 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Intelligence ; Neurology ; Neuropsychology ; Phenylketonuria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004310050945
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  • 5
    Digitale Medien
    Digitale Medien
    Phenylalanine hydroxylase genotypes, predicted residual enzyme activity and phenotypic parameters of diagnosis and treatment of phenylketonuria (1996)
    Springer
    European journal of pediatrics 155 (1996), S. S11 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Phenylketonuria ; Genotype ; Treatment ; IQ
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00014222
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  • 6
    Digitale Medien
    Digitale Medien
    Intelligence and professional career in young adults treated early for phenylketonuria (1996)
    Springer
    European journal of pediatrics 155 (1996), S. S97 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Key words Phenylketonuria ; Intelligence ; Education ; Professional career ; Phenylalanine ; control
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: 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.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/PL00014262
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  • 7
    Digitale Medien
    Digitale Medien
    Continuation vs discontinuation of low-phenylalanine diet in PKU adolescents (1987)
    Springer
    European journal of pediatrics 146 (1987), S. A17 
    Details
    ISSN: 1432-1076
    Schlagwort(e): Phenylketonuria ; Adolescents ; Dietary control ; Intelligence ; Psychological problems
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00442050
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  • 8
    Digitale Medien
    Digitale Medien
    Preparation and properties of composites of kevlar-nomex copolymer and boehmite (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 248 (1997), S. 139-151 
    Details
    ISSN: 0003-3146
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Ein neuartiges organisch-anorganisches Hybridmaterial wurde durch den Einbau des Minerals Böhmit mittels eines Sol-Gel-Prozesses in ein Kevlar-Nomex-Copolymeres hergestellt. Durch Reaktion eines Gemisches aus m- und p-Phenylendiamin mit Terephthaloylchlorid und anschließender Umsetzung mit Aminophenyltrimethoxysilan wurden Poly(phenylenterephthalamid)-Ketten mit Aminophenyltri-methoxysilan-Endgruppen synthetisiert. In dieser Polymermatrix wurde die Hydrolyse der Alkoxygruppen einer Lösung von Aluminium-sec-butanolat in Butanol durchgeführt. Dadurch wurde ein chemisch an die Aramid-Ketten gebundenes anorganisches Netzwerk aufgebaut. Aus den hergestellten Hybridmaterialien mit unterschiedlichen Böhmit-Gehalten in der Aramidmatrix wurden Filme gegossen. Die Filme aus Hybridmaterial mit bis zu 15 Gew.-% Böhmit waren transparent gelb, während bei 20 und mehr Gew.-% Böhmit opake Filme erhalten wurden. Die mechanischen Eigenschaften dieser Filme wurden untersucht. Zugfestigkeit, Zugmodul, Härte und maximale Bruchdehnung nahmen mit steigendem Böhmitgehalt zunächst zu, vemngerten sich jedoch bei weiterer Erhöhung des Mineralanteils wieder. Der Zugmodul des Hybridmaterials bei 25°C lag zwischen 3,0 und 4,5 GPa. Die Materialien hielten einer maximalen Zugspannung von 252 MPa stand und zeigten Zersetzungstemperaturen von etwa 450°C. Die rnit DMTA ermittelten Werte für den Speichemodul lagen im Bereich 7,6-18,9 GPa. Das tan δ-Signal verbreiterte sich mit zunehmendem Böhmitanteil und ging bei hohen Böhmitgehalten in eine Schulter über. Die Signalpositionen des Verlustfaktors wurden infolge der zunehmenden sterischen Einschränkung der Segmentbewegungen rnit steigendem anorganischen Anteil zu höheren Temperaturen verschoben.
    Notizen: A new organic-inorganic hybrid material was prepared by incorporating boehmite into a Kevlar-Nomex copolymer via a sol-gel process. Poly(phenylene-terephthalamide) chains having aminophenyltrimethoxysilane end groups were prepared by reacting a mixture of m-and p-phenylenediamine with terephthaloyl chloride, followed by end-capping with aminophenyltrimethoxysilane. The hydrolysis of the alkoxy groups of an aluminium sec-butoxide solution in butanol was carried out in the polymer matrix, thus creating an inorganic network structure combined chemically with the aramid chains. Hybrid materials containing different proportions of boehmite in aramid were thus produced and films were cast by solvent evaporation technique. These films with up to 15 wt.-% of boehmite were yellow and transparent, whereas the films with 20 wt.-% or more contents of boehmite were opaque. Mechanical properties of these films were analyzed. The values of tensile strength, initial modulus, toughness and maximum strain at rupture were initially found to increase and then decrease with further addition of boehmite. The tensile modulus of the hybrid material was found to be in the range of 3.0-4.5 GPa at 25°C. These ceramers were found to withstand maximum tensile stress of the order of 252 MPa, and the thermal decomposition temperature was around 450°C. The storage modulus as measured using DMTA was in the range of 7.6-18.9 GPa. The tan δ peak which in general became broader with increasing boehmite content showed a shoulder for composites containing large amounts of boehmite. The position of the peaks shifted towards high temperature with the increase in the inorganic contents showing hindrance in motion with increasing boehmite contents.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/apmc.1997.052480109
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  • 9
    Digitale Medien
    Digitale Medien
    Neue Sol-Gel-Beschichtungen als Korrosions-und Verschleißschutz für NE-Metalle (1998)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 29 (1998), S. 23-29 
    Details
    ISSN: 0933-5137
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Beschreibung / Inhaltsverzeichnis: New Sol-Gel Based Coatings as Corrosion- and Wear-Protection On Non-Ferrous MetalsA new composite coating material has been developed for the protection of non-ferrous alloys (e.g. aluminum, magnesium, zinc and brass). The coating materials were prepared by the solgel process from epoxyalkoxysilanes and aromatic diols to act as crosslinking agents. As solvent, alcohols and glycol ethers have been used.The viscosity of the system (7-55 mPas) was established in a way to be used in spray, dip or flow coating processes. The transparent coatings were cured at T = 100-220°C. In corrosion tests, 3000 hours salt-spray climate and 240 hours CASS-test = Copper chloride and Acetic acid added Salt Spray, no infiltration of the metal-coating interface and no „filiform-corrosion“ on A199.5, AlMg3 and AlMgSil was observed. Brass samples showed less than 4 mm extension of a scribe after 500 hours salt-spray-test. The coatings showed no visible traces of abrasion after 1000 cycles taber abrader test and an excellent adhesion (cross cut and tape-test: grade 0). The transparent basic systems were pigmented by 5 - 10 wt.% of colored organic pigments to obtain all kind of colored coatings.
    Notizen: Es wurde ein neuer Beschichtungswerkstoff auf Basis von anorganisch-organischen Kompositen zum Schutz von Metalloberflächen, besonders von Aluminium entwickelt. Das Beschichtungsmaterial wurde über den Sol-Gel-Prozeß synthetisiert, ausgehend von Epoxy-funktionalisierten Alkoxysilanen und aromatischen Diolen als Quervernetzer. Als Lösungsmittel wurden Alkohole und Glykolether verwendet.Die Viskosität der Systeme wurde so eingestellt, daß sowohl Sprüh-, als auch Tauch- und Flut-Beschichtungen durchgeführt werden konnten. Sie lag zwischen 7 und 55 mPas. Nach dem thermischen Verdichtungsprozeß bei 100-220°C wurden transparente Beschichtungen mit ausgezeichneter Haftung auf Al-Mg-, Zn-und Messing-Oberflächen (Gitterschnitt- und Tape-Test: Klasse 0) erhalten. Die Korrosionsfestigkeit beschichteter Aluminiumlegierungen (Al 99.5, AlMg3, AlMgSi I) wurde mit dem Salzsprühverfahren (DIN 50021) und dem CASS-Test (NaCl, CuCl2·2H2O, Essigsäure, pH=3) geprüft und auch nach 3000 Stunden trat keine Unterwanderung der Grenzfläche Metall / Schicht auf. Ebenso wurde keine „Filiform“-Korrosion beobachtet. Messingproben zeigten nach 500 h Salzsprühnebel-Test weniger als 4 mm mittlere Unterwanderungsbreite. Darüber hinaus wurde die Abriebbeständigkeit der Proben überprüft. Die Schichten zeigten keine sichtbare Beschädigung nach Prüfung des Abriebes mit dem Reibradverfahren (1000 Zyklen, Räder: CS 10-F).Es konnten stabile Dispersionen von organischen Farbpigmenten im transparenten Basissystem hergestellt werden, wodurch eine große Vielfalt farbiger Beschichtungen erhalten wurde.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mawe.19980290108
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  • 10
    Digitale Medien
    Digitale Medien
    Einfluß von HCl und Cl2 auf die Hochtemperaturkorrosion des 2 1/4 Cr 1 Mo-Stahls in Atmosphären mit hohen Sauerstoffdrücken (1990)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 41 (1990), S. 303-307 
    Details
    ISSN: 0947-5117
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Beschreibung / Inhaltsverzeichnis: Influence of HCl and Cl2 on high temperature corrosion of 2 1/4Cr 1 Mo Steel in atmospheres with high oxygen pressuresThe oxidation of the 2 1/4 Cr 1 Mo steel was investigated at 773 K in oxidizing He-O2-HCl atmospheres. The addition of HCl to He-O2 atmospheres leads to accelerated oxidation rates. Below porous and cracked oxide scales condensed chlorides are formed. At low HCl pressures 0-1000 vppm the “active oxidation” is determining the corrosion process; i.e. oxidation of evaporating chlorides within the oxide scale. For higher HCl contents 1000-3000 vppm the corrosion behaviour changes to paralinear; i.e. simultaneous parabolic oxide growth and linear mass loss by chloride evaporation.
    Notizen: Die Oxidation des 2 1/4Cr1Mo-Stahls in oxidierenden He-O2-HCl-Atmosphären bei 773 K wurde untersucht. Der Zusatz von HCl zu He-O2-Atmosphären führt zu stark beschleunigter Oxidation. Unter porösen und rissigen Oxidschichten bilden sich feste Chloride. Bei niedrigen HCl-Drücken 0-1000 vppm bestimmt „aktive Oxidation“ den Korrosionsprozeß; d.h. Oxidation flüchtiger Chloride innerhalb der Oxidschicht. Bei höheren HCl-Drücken 1000-3000 vppm erfolgt ein Übergang zum paralinearen Korrosionsverhalten, d.h. gleichzeitiges parabolisches Oxidwachstum und lineare Massenabnahme durch das Abdampfen von Chloriden.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/maco.19900410602
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