Spectrum of phenylketonuria mutations in Western Europe and North Africa,and their relation to polymorphic DNA haplotypes at the phenylalanine hydroxylase locus

Summary A total of 252 chromosomes from 126 patients with phenylalanine hydroxylase (PAH) deficiencies were analyzed for both mutant genotypes and restriction fragment length polymorphism (RFLP) haplotypes at the PAH locus. The mutant genes studied originated either from Western Europe (116 alleles) or from Mediterranean countries (136 alleles). Only 27% of all mutant alleles were found to carry identified mutations, particularly mutations at codon 252 (2.3%), 261 (7.5%), 280 (6.3%), 408 (3.5%) and at the splice donor site of intron 12 (6.3%). The mutant genotypes were associated with RFLP haplotypes 7, 1, 38, 2 and 3 at the PAH locus respectively. Except for the splice mutation of intron 12, these associations were preferential, but not exclusive, since the other four mutations were found on the background of at least two RFLP haplotypes. These results, together with the observation that 85% of PAH deficient patients are heterozygotes for their mutant genotypes, emphasize the great heterogeneity of PAH deficiencies in Mediterranean countries and hamper systematic DNA testing for carrier status in this population.     

Use of a simple method for the Epstein-Barr virus transformation of lymphocytes from members of large families of Réunion Island

A simple method for the preparation of lymphoblastoid cell lines from small amounts (100 microliter) of frozen whole blood is described. A success score greater than 90% was obtained for EBV transformations using blood samples which had been collected several months before the infection. Due to the simplicity of the technique, up to 80 samples could be processed per day. This technique was used to prepared 242 permanent cell lines from 13 large families from Réunion Island showing blood group H deficiency. These cell lines are now available for genetic studies.     

Organogenesis at the shoot apex: An attempt at modelization

A geometrical model of the emergence of a primordium at the shoot apex in dicotyledons is proposed. It is based on recent fundamental results on plant morphogenesis, i.e.:

1. the emergence is preceded by the reorganization of the microtubules of the cortical cytoskeleton, leading to a new orientation of the synthesis of the cell wall microfibrils;
2. the resulting global stress is related to the general orientation of the cell growth.

So the model sums up the continuous interactions linking the microtubules, the microfibrils and the cell growth axis. This paper tries to answer three questions which are essential from a botanical point of view:

1. Why does the principal stem shift its growth direction after each lateral emergence?
2. Why do the three axes involved in any ramification (namely the old and the new principal stems and the lateral emergence) exhibit a plane configuration whereas this is an essentially three dimensional phenomenon?
3. Does phyllotaxis exclusively depend upon the local emergence of a primordium?

A come and go between the botanical knowledge and the mathematical model leads to an integrated view of the compatibility mechanisms linking the different microtubules and microfibrils networks, without forgetting the apical dome restoration. A geometrical formalism allows a modern redefinition of both the “generating centre” and the “organizing centre” and their field effects.     

CFC syndrome: a syndrome distinct from Noonan syndrome

We report two children with a common pattern of birth defects. Both have very sparse, curly hair, nystagmus and mental retardation. The first one has Noonan syndrome habitus associated with keratosis plantaris and nystagmus; the second one has a slightly Noonan-like face, macrocephaly, keratosis pilaris, and hypertrophic cardiomyopathy. They represent the extreme of a spectrum of congenital defects recently reported independently as CFC syndrome by Reynolds and as "Noonan-like short stature syndrome with sparse hair" by Baraitser and Patton. The clinical features are reviewed and the autonomy of the syndrome with regards to Noonan syndrome, is disputed, since every sign seems to occur independently in Noonan syndrome. The father of the second case probably has a minor syndrome expression, pointing to probable autosomal dominant inheritance.     

The distribution of oocyte 5S,somatic 5S and 18S + 28S rDNA sequences in the lampbrush chromosomes of Xenopus laevis

The nucleolus organizer locus of Xenopus laevis lampbrush chromosomes was identified by in situ hybridization of a ³H-labelled probe complementary to 18S + 28S rDNA. The nucleolus organizer is an axial granule on chromosome III that lies four-fifths the way down this chromosome reading from its larger (left) telomere, just within an exploded region that extends to its right end, where the lateral loops are exceptionally long. By in situ hybridization of ³H-labelled oocyte and somatic 5S spacer cRNA probes to similarly RNase-treated and denatured lampbrush chromosomes, the multiple sites of oocyte and somatic 5S gene families were identified. Oocyte 5S genes lie at the larger telomeres of the 15 chromosomes that possess these structures; that is, all but chromosomes X, XVII and XVIII. There are a further four sites, all peripheral, and in three of these, on chromosomes VII, X and XI, the sequences lie on lateral loops that are resolvable with the light microscope. By contrast all of the somatic 5S gene clusters occupy peripheral sites. There are two sites on chromosome III, one of which may be shared with oocyte 5S sequences; one on chromosome VII, which is very likely shared with oocyte 5S sequences; one terminal site on chromosome X; one site on chromosome XI that lies on a single pair of long loops which are inserted in a conspicuous and recognizable axial granule, loops which certainly carry oocyte 5S sequences too; two nearly terminal sites alongside the larger telomeres on chromosomes XII and XIV; and single interstitial sites on all three of the sphere-bearing chromosomes, VIII, IX and XVI. We suggest that 5S sequences on resolvable loops are transcribed by readthrough from upstream promoters, probably by polymerase II.     

Evidence for heterogeneity of low-density lipoprotein metabolism in the cynomolgus monkey

Preliminary studies were performed to establish whether there was kinetic heterogeneity in the metabolism of subclasses of low-density lipoproteins (LDL) in the cynomolgus monkey. Previous studies of the effects of inhibition of hepatic triglyceride lipase in this species had shown an increase in the mass of lighter LDL (Sf greater than 9) and a decrease in the mass of denser LDL. LDL (1.019 less than d less than 1.063) were subdivided into two subfractions LDL1 (1.019 less than d less than 1.035) and LDL2 (1.035 less than d less than 1.063) by ultracentrifugation. The lipoproteins in these two fractions could be shown to have different flotation by analytic and isopycnic ultracentrifugation. When tracer amounts of homologous 125I-labeled very-low-density lipoproteins (VLDL) were injected into chow-fed cynomolgus monkeys, apoB radioactivity appeared in LDL1 prior to its appearance in LDL2. [125I]LDL1 injected into the monkey was removed from the LDL1 density subclass with a half-life of 5.5-10.3 h. Much of the radioactivity injected as LDL1 was converted to denser LDL (LDL2). Labeled LDL2 injected into the monkey was not converted to LDL1. Thus, at least two kinetically distinct subpopulations of LDL circulate in the plasma of this species. The lighter LDL is to a large extent a metabolic precursor of the more dense LDL (LDL2).     

Regeneration of NAD(+) cofactor by photosensitized electron transfer in an immobilized alcohol dehydrogenase system

The irradiation with visible light of a photosensitizer dye like methylene blue was used to regenerate by electron transfer the oxidized form of a pyridine nucleotide coenzyme (NAD(+)). The process has been studied on a common enzymatic reaction: ethanol oxidation by alcohol-NAD(+) oxidoreductase immobilized on polyacrylamide gel or porous glass balls. In the experimental conditions used, the initial NAD(+) recycling rates were 2.33 x 10(4) cycles/h (polyacrylamide) and 3 x 10(4) cycles/h (glass balls). A total number of 49.5 x 10(4) cycles was obtained for 13 runs of 2 h. The enzyme immobilization strongly increased its stability: after 28 days at 20 degrees C, the residual activity was 25% of the initial value.     

Antigenic, functional, and molecular genetic studies of human natural killer cells and cytotoxic T lymphocytes not restricted by the major histocompatibility complex

Cytotoxicity not restricted by the major histocompatibility complex (MHC) is mediated by two distinct types of lymphocyte: natural killer (NK) cells and non-MHC-restricted cytotoxic T lymphocytes (CTL). These two types of cytotoxic lymphocytes can be distinguished by antigenic phenotype, function, and molecular genetic studies. In human peripheral blood, NK cells are identified by expression of the Leu-19 and/or CD16 cell surface antigens, and lack of CD3/T cell antigen receptor (Ti) complex expression (i.e., CD3-,Leu-19+). Peripheral blood non-MHC-restricted CTL express both CD3 and Leu-19 (i.e., CD3+, Leu-19+, referred to as Leu-19+ T cells). Both Leu-19+ T cells and NK cells lyse "NK-sensitive" hematopoietic tumor cell targets, such as K562, without deliberate immunization of the host. However, most "NK activity" in peripheral blood is mediated by NK cells, because they are usually more abundant and more efficient cytotoxic effectors than Leu-19+ T cells. The cytolytic activity of both NK cells and Leu-19+ T cells against hematopoietic targets was enhanced by recombinant interleukin 2 (rIL 2). NK cells, but not peripheral blood Leu-19+ T cells, were also capable of lysing solid tumor cell targets after short-term culture in rIL 2. Southern blot analysis of NK cells revealed that both the T cell antigen receptor beta-chain genes and the T cell-associated gamma genes were not rearranged, but were in germ-line configuration. These findings indicate that NK cells are distinct in lineage from T lymphocytes and do not use the T cell antigen receptor genes for target recognition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Modifications of sphingomyelin and phosphatidylcholine metabolism by tricyclic antidepressants and phenothiazines

Phenothiazines and tricyclic antidepressants, when added to culture medium, gave rise in several types of cells (C6 rat glioma cells and human fibroblasts), to a decrease in lysosomal sphingomyelinase activity. The effect of chlorpromazine and desipramine was dose dependent, and was observed after 3 hours of incubation with the drugs at concentrations ranging between 1 and 10 microM. In C6 glioma cell cultures, the decrease in sphingomyelinase activity was related to the clinical effectiveness of phenothiazines, tricyclic antidepressants and derivatives. Incorporation of (choline-14C) sphingomyelin showed that the metabolic pathway implying the synthesis of phosphatidylcholine from the hydrolysis of sphingomyelin and/or transfer of phosphorylcholine to phosphatidylcholine was also partially reduced.