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M Neugebauer

Publications and source records attributed to M Neugebauer.

At least 19 recordsLinked to original sources
PubMed2006

Determination of aflatoxin B1 in tiger nut-based soft drinks.

An analytical method for the determination of aflatoxin B1 in a tiger nut-based soft drinks named 'horchata' is described. The method is based on an immunoaffinity clean-up, followed by HPLC separation and fluorescence detection after electrochemical post-column derivatization. The detection limit (S/N = 3) and the quantification limit (S/N = 10) were 0.02 and 0.06 microg kg(-1), respectively. The mean recovery at a level of 2 microg l(-1) was 88% (n = 6) and the coefficient of variation was 9%. The method was applied to conduct a small market survey for a beverage named 'horchata' that is frequently consumed by parts of the population in Southern Europe. Twenty-two samples from Spanish and Belgian supermarkets were analysed. As a result, only one sample was found to contain aflatoxin B1 at the limit of quantitation of the method.

Aflatoxin B1↗
PubMed1995

[Biotransformation of (+)-methamphetamine in fertile hen's eggs].

On application of (+)-methamphetamine (1) to the albumen of embryonated hen's eggs it is possible to detect phase I as well as phase II metabolites of 1 in the allantois liquid. When application is effected on the first day of incubation, methamphetamine is less toxic than when effected on the sixth day of incubation. Besides unchanged 1 ten metabolites have been identified. Principal pathways of biotransformation are N-dealkylation as well as aromatic p-hydroxylation and--as phase II reactions--N-acetylation and other conjugation reactions. The total amount of the metabolites produced depends on time of incubation and is up to about 25% of the applied dose. Differences from, but also similarities to human metabolism have been noticed. Consequently, the experiment is likely to be suitable as an alternative method for testing biotransformation reactions.

Acetylation↗
PubMed1994

An estimate on the frequency of duplicated haplotypes and silent alleles of human C4 protein polymorphism. II. Investigations in healthy Negro families.

The first investigation of complete MHC marker data in South African Negroes by segregation analysis in 11 families with up to three generations is presented, including quantitative evaluation of C4 allotype patterns and C4 beta chain determinations according to Steuer et al. (1). The frequency of homo- and heteroduplicated, hybrid, and non-expressed C4 alleles was determined from C4 protein phenotyping, including C4 alpha and beta chains, quantitative estimates of the relative electrophoretic C4 banding patterns by scanning densitometry, and from the other classical MHC markers by submitting all results to the family analysis program (FAP). From unrelated non-diseased individuals (n = 105) in these families with 62 haplotypes, the following frequencies were observed for non-expressed alleles: C4A*Q0 0.1189, C4B*Q0 0.2552, and for the total of heteroduplicated alleles: C4A 0.0645, C4B 0.0608. Applying additionally quantitative determinations of C4 banding patterns, homoduplications such as C4A*3 A*3, C4B*1 B*1, C4B*3 B*3, and the heteroduplication C4A*3 A*2 were assumed. In the investigated individuals the heteroduplications of C4A*12 and C4A*3 with the A*91 allele and of C4B*2 with C4B*92 were observed. It was concluded that not only allele frequencies but also the frequency of heteroduplications seems to be of specific ethnic character. Furthermore, the prior hypothesis that deletion or non-expression at one C4 locus is accompanied by duplication at the other was only confirmed for non-expressed B-alleles with C4A*3 A*91 or C4A*12 A*91.(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1994

Recombination fractions in the HLA system based on the data set 'provinces Françaises': indications of haplotype-specific recombination rates.

In the large genetic survey "Provinces Françaises' the recombination fractions in the HLA system have been estimated by a family analysis programme (FAP). A total of 1332 families were analysed and in general the findings were in agreement with recombination fractions reported previously. The maternal recombination rates were on average 1.8 times higher than the corresponding ones for males. The comparison of the recombination fractions with the corresponding physical distances suggests the existence of hot spots of recombination. The analysis did not show deviations from expected values for HLA-A and B alleles on HLA-A/B recombinant haplotypes. However, analysis of HLA-B/DR recombinant haplotypes showed a skewed distribution of B and DR alleles. The significance of the findings is difficult to evaluate as all results are estimated numbers and frequencies but a manual analysis of the recombinant families confirmed the observations. HLA-B/DR recombinant haplotypes carried often HLA-DR3 and DR11 whereas DR2 and DR7 were more rarely present on recombinant haplotypes. DR4 had an increased incidence on BF/DR recombinant haplotypes but not on A/B or B/BF recombinant haplotypes. Some of the haplotypes with the strongest linkage disequilibria as A1,B8,DR3 and A3,B7,DR2 seem to be less frequently involved in recombinations than other haplotypes. Variations of recombination rates depending on certain alleles or haplotypes might partially explain the conservation of some haplotypes or part of haplotypes in Caucasoids.

Alleles↗
PubMed1992

[Synthesis of metabolites and enantiomers of prolintane].

The synthesis of 15 possible metabolites of prolintane (1) (Katovit) which is used in the treatment of blood pressure disregulations is described. Furthermore, the preparation of the enantiomers of 1 is reported, starting with R-(+)- and S-(-)-phenylalaninol respectively.

Pyrrolidines↗
PubMed1992

Study on the metabolism of racemic prolintane and its optically pure enantiomers.

1. Asian and European volunteers were given racemic prolintane, and the metabolites in the 24 h urine were identified and quantified by g.l.c. mass spectroscopy using synthetic reference compounds. 2. R-(+)- and S-(-)-prolintane were synthesized from optically active phenylalanine. The metabolism of the enantiomers differs mainly in the quantitative amounts of metabolites.

Adult↗
PubMed1991

MASA syndrome: clinical variability and linkage analysis.

We report on a family with three males with MASA syndrome (mental retardation, aphasia, shuffling gait, and adducted thumbs). One patient demonstrated spastic paraplegia and psychomotor retardation but no adducted thumbs. The described family underlines the clinical variability in MASA syndrome. DNA studies confirm linkage to DNA markers of the Xq28 region. Analysis of published cases with hereditary spastic paraplegia (HSP), where linkage studies have been carried out, emphasizes the clinical variability in MASA syndrome and other types of HSP, thus making a definite diagnosis in single cases often impossible.

Aphasia↗
PubMed1991

Essential Oils of Achillea ptarmica.

Using GC and GC/MS, 40 compounds were identified in the essential oils of various organs of ACHILLEA PTARMICA. Three ponticaepoxides and (+)-(4 S,6' R)-beta-sesquiphellandrene could be isolated from the root.

Journal Article↗
PubMed1990

[Lactones. 22. Synthesis and reduction of alpha-aminomethylene-delta,delta-diphenyl-delta-valerolactones].

Treatment with tris-(dimethylamino)-methane resp. formylation and reaction with piperidine transfer 1 to 5a,b, which can not be reduced to the corresponding alpha-aminomethyllactones 4a,b, in contrast to the homologue 6 and other alpha-aminomethylene-gamma- and delta-lactones. Isolation of products and gc/ms-investigations verify the reaction course: The aminomethyl moiety in alpha-position of delta,delta-diarylated delta-lactones is instable and eliminates amine to give 7 (NaCNBH3) or 9 (H2/Pt). Only cleavage of the lactone ring enables the formation of stable aminomethyl compounds (10,11). 5a shows weak parasympatholytic and no H1-antihistaminic activity at the isolated guinea-pig ileum.

Animals↗
PubMed1990

Acetylenes from Atractylis koreana.

A reinvestigation of the rhizomes of ATRACTYLIS KOREANA afforded in addition to 1,3-diacetoxytetradeca-6,12-diene-8,10-diyne reported previously (1) two new C (14)-polyacetylenes with an ene-diyn-ene-chromophor and one new C (14)-polyacetylene beside two known compounds with an ene-diyne-diene-chromophor. Their structures were established by spectroscopic and chemical methods.

Journal Article↗
PubMed1990

Posthumous diagnosis of X-linked retinoschisis using DNA analysis.

X-linked juvenile retinoschisis usually results in a rather serious visual handicap in affected males. However, occasionally patients can present with very subtle clinical signs without subjective complaints. For this reason, the family history can be misleading and caution is necessary when analysing the pedigree and giving genetic advice. In this report a family with X-linked retinoschisis is described in which segregation analysis with DNA probes strongly suggests that the deceased grandfather, who was said to have had good vision, had been affected by juvenile retinoschisis.

DNA↗
PubMed1989

Genetic analysis of IDDM: the GAW5 multiplex family dataset.

In a collaborative effort by 12 centers from Europe and North America, data were assembled from 94 multiplex families with insulin-dependent diabetes mellitus (IDDM) for analysis of genetic and other factors of possible etiological importance. The dataset contains information on the following genetic markers: HLA-DR beta and -DQ beta restriction fragment length polymorphisms (RFLPs), three RFLPs detected with two probes that map 5' to the insulin gene, the serologically defined HLA loci, and the immunoglobulin allotypes. Data also were included for auto-antibodies to insulin and pancreatic islet cells as possible indicators of pathogenesis and for antibodies to certain viruses that have been implicated as "triggering" agents in IDDM. Medical history of family members was obtained by means of a uniform questionnaire. Identical copies of the dataset were distributed to anyone wishing to participate in the analysis for the IDDM component of GAW5. The multiplex IDDM family dataset is now available on request for further analysis.

Adolescent↗
PubMed1989

Association and sibpair analysis for the HLA, Gm, Km, and insulin polymorphisms in multiplex IDDM families.

A log-linear model was used to analyze three-way interactions between IDDM and pairs of genetic markers. To do this, a special sample dataset was selected by taking one affected and one unaffected child from each family. Some three-way interactions were found for associations between insulin-dependent diabetes mellitus (IDDM), HLA-DR, and DQ restriction enzyme fragment length polymorphism (RFLP) patterns. No three-way interaction was found for IDDM, HLA-DR, and Gm or Km. An extended sibpair analysis was applied to the HLA-B,DR loci and to the Gm, Km, and insulin gene polymorphisms. The well-known result for IDDM and HLA was reproduced. For Gm, Km, and the insulin gene no cosegregation with IDDM could be found.

Child↗
PubMed1989

Gene of X-chromosomal congenital stationary night blindness is closely linked to DXS7 on Xp.

Congenital stationary night blindness is characterized disturbed or absent night vision that is always present at or shortly after birth and nonprogressive. The X-linked form of the disease (CSNBX; McKusick catalog no. 31050) differs from the autosomal types in that the former is frequently associated with myopia. X-chromosome-specific polymorphic DNA markers were used to carry out linkage analysis in three European families segregating for CSNBX. Close linkage without recombination was found between the disease locus and the anonymous locus DXS7, mapped to Xp11.3, assigning the mutation to the proximal short arm of the X chromosome. Linkage data obtained with markers flanking DXS7 provided further support for this localization of the gene locus. Thus, in addition to retinitis pigmentosa and Norrie disease, CSNBX represents the third well-known hereditary eye disease the locus of which is mapped on the proximal Xp and closely linked to DXS7.

Chromosome Mapping↗
PubMed1989

An estimate on the frequency of duplicated haplotypes and silent alleles of human C4 protein polymorphism. I. Investigations in healthy Caucasoid families.

The frequency of duplicated and non-expressed C4 alleles was determined by segregation analysis in 31 German and five French families with altogether 274 individuals by submitting the complete data from C4 protein phenotyping, including C4 beta chains, and the other classical MHC markers to the family analysis programme (FAP). From 120 unrelated German haplotypes the following frequencies were derived for silent alleles: C4A*Q0 0.2000, C4B*Q0 0.2083, and for the total of homo- and heteroduplicated C4A resp. C4B alleles: C4"DA"* 0.1333, C4"DB"* 0.1000. The true occurrence of the duplicated C4A*2, "DB*21" haplotype, first observed in French families, was found to be 0.0250 in the German sample. While the frequency of duplicated C4 haplotypes confirms earlier estimates, the increase in the frequency of silent alleles corresponds to those assumed from investigations at the DNA level. The results demonstrate classical protein typing with inclusion of C4 beta chain types to be an indispensable and powerful tool for haplotype recognition; they support the hypothesis that deletion at one C4 locus is accompanied by duplication at the other in a majority of haplotypes.

Alleles↗
PubMed1989

[Norrie syndrome: identification of carriers by segregation analysis with flanking DNA markers].

Norrie disease is an X-linked recessive disorder. Affected males present with congenital blindness. Additionally, hearing loss and psychotic behavior may occur at any time. Since carriers are clinically healthy, they can only be identified by genetic means. Daughters of carriers or sisters of affected males have an à priori 50% risk of being carriers themselves. Close linkage has been found between the Norrie disease locus (NDP) and the DNA locus DXS7 mapped to Xp11.3. For genetic counselling, this linkage relationship allows carriers of the disease to be identified in informative families. We describe a large pedigree with Norrie disease. Segregation analysis was carried out with DXS7 and a second flanking marker, DXS255, both linked to NDP. In this way, three females at risk were identified who had a high probability of being carriers for Norrie disease.

Adult↗