Francoise Rey

A European multicenter study of phenylalanine hydroxylase deficiency: Classification of 105 mutations and a general system for genotype-based prediction of metabolic phenotype

Phenylketonuria (PKU) and mild hyperphenylalaninemia (MHP) are allelic disorders caused by mutations in the gene encoding phenylalanine hydroxylase (PAH). Previous studies have suggested that the highly variable metabolic phenotypes of PAH deficiency correlate with PAH genotypes. We identified both causative mutations in 686 patients from seven European centers. On the basis of the phenotypic characteristics of 297 functionally hemizygous patients, 105 of the mutations were assigned to one of four arbitrary phenotype categories. We proposed and tested a simple model for correlation between genotype and phenotypic outcome. The observed phenotype matched the predicted phenotype in 79% of the cases, and in only 5 of 184 patients was the observed phenotype more than one category away from that expected. Among the seven contributing centers, the proportion of patients for whom the observed phenotype did not match the predicted phenotype was 4%-23% (P<.0001), suggesting that differences in methods used for mutation detection or phenotype classification may account for a considerable proportion of genotype-phenotype inconsistencies. Our data indicate that the PAH-mutation genotype is the main determinant of metabolic phenotype in most patients with PAH deficiency. In the present study, the classification of 105 PAH mutations may allow the prediction of the biochemical phenotype in >10,000 genotypes, which may be useful for the management of hyperphenylalaninemia in newborns.

Identification and antigenicity of the major envelope glycoprotein of lymphadenopathy-associated virus

The major envelope glycoprotein of the causative agent of Acquired Immune Deficiency Syndrome (AIDS) lymphadenopathy-associated virus (LAV) has been identified and characterized. The glycoprotein has an apparent molecular weight of 110,000-120,000 under denaturing conditions in polyacrylamide gel electrophoresis. Upon deglycosylation by a specific endoglycosydase, its size is reduced to 80,000. Cellular precursors of this glycoprotein have been detected with apparent molecular weight of 150,000 and 135,000. Nearly all AIDS and pre-AIDS patients have detectable antibodies against this viral glycoprotein.

Nucleotide sequence of HIV1-NDK: a highly cytopathic strain of the human immunodeficiency virus

A highly cytopathic strain of HIV1, named HIV1-NDK, has been isolated from a Zaïrian patient affected with AIDS. This isolate is 10(4) times more cytopathic and infectious than the prototype. To correlate the high cytopathic properties of this strain with genetic variations, we have cloned and sequenced the genome of this isolate. The principal feature which could be drawn from the fine analysis of the HIV1-NDK sequence is that the variability is not clustered in one particular region but rather spread out all along the genome. Only minor differences seem to be responsible for the acute biological effect of HIV1-NDK.

Neuropsychologic Functions of Early Treated Patients with Phenylketonuria, on and off Diet: Results of a Cross-National and Cross-Sectional Study

Twenty-two French patients with early treated phenylketonuria (PKU) off diet (no reduced phenylalanine, Phe) since their 5th birthday, 23 German patients on diet (reduced Phe), and 21 healthy control subjects from childhood to adulthood matched for age, sex, and IQ were investigated for visuomotor reaction time, sustained attention, and visual stimulus scanning. Determinations were made whether 1) the three groups showed different developmental trends in their reaction times, 2) the threshold of a Phe blood level of 360 μmol/L formulated in recent recommendations can be regarded as safe, 3) test performances are related to the quality of dietary control in the same way for all age groups, and 4) long-term elevated Phe levels result in aggravating effects of increasing differences between patients on and off diet and healthy controls. Results revealed that developmental trends were similar in all treatment groups. Only children with a mean Phe level below 360 μmol/L performed as well as control subjects. Differences between treatment groups decreased in adulthood, and no aggravating effect could be observed. Mean performance of patients with mild PKU off diet was in the same range as performance of patients with classical or mild PKU on diet, calling into question the benefit of treating these patients. It is concluded that it is preferably safer to maintain Phe blood levels below 360 μmol/L at least during the first 10 y of life.

Isolation of human T-lymphotropic retrovirus (LAV) from Zairian married couple, one with AIDS, one with prodromes.

A Zairian married couple had been living in France since 1981. The man had acquired immunodeficiency syndrome (AIDS) and his wife had prodromes of the disorder. Infection with a human T-lymphotropic retrovirus (lymphadenopathy-associated virus) was demonstrated in both by isolation of the virus from their cultured lymphocytes and the detection of specific antibodies in serum samples. Since this virus has been isolated from patients in other AIDS risk categories, the finding of the virus in AIDS patients from the African group adds further support to the hypothesis that this human retrovirus is the AIDS aetiological agent.

Detection and titration of neutralizing antibodies to HIV using an inhibition of the cytopathic effect of the virus on MT4 cells

An assay for determining neutralizing antibodies in sera from individuals infected with HIV was developed. This assay is based on an inhibition of the cytopathic effect observed after HIV superinfection of the HTLV-1-positive cell-line MT4. Only about 10% of asymptomatic seropositive donors exhibit a high titre over 1/500 up to 1/2000 while in 60% of sera, neutralizing antibodies were not detected. The assay reported here can also be used for the comparison of the biological properties of the different strains of HIV.

A new type of retrovirus isolated from patients presenting with lymphadenopathy and acquired immune deficiency syndrome: Structural and antigenic relatedness with equine infectious anaemia virus

Summary Further characterization of a human lymphotropic retrovirus previously isolated from a patient with lymphadenopathy syndrome is reported. The virus is not antigenically related to human T-cell leukaemia virus (HTLV1). The mature virions have a distinct morphology when examined by electron microscopy, with a small eccentric core. This morphology is close to that of equine infectious anaemia virus (EIAV). Moreover, the p25 protein of the human isolate can be immunoprecipitated by sera of horses infected with EIAV. Similar viral isolates have been made from several patients with acquired immune deficiency syndrome (AIDS). Antibodies to such viruses are widely distributed in patients having AIDS or at risk of AIDS.

Influence of Flow Rate on the Kinetics of the Intestinal Absorption of Glucose and Lysine in Children

We studied the influence of flow rate on the kinetics of glucose and lysine absorption in 20 normal children, ages 7 months to 5 years, by using a double lumen tube. In certain substrate concentration and flow rate ranges, absorption was found to increase proportionally to the flow rate without altering the maximum capacity of the segment and without a significant decrease of the concentration gradient along the segment; this proves that in these conditions, perfusion rate does not increase the surface of mucosa really perfused. It was also shown that this effect is related to modifications of the apparent affinity constants. It is proposed that the flow rate altered the thickness of the unstirred water layers lining the microvilli, and, consequently the substrate concentrations at the contact of the transport sites. Assuming this, our results could further suggest that molecular diffusion through these water layers may be rate-limiting in the over-all process of absorption, even for hydrosoluble substrates such as glucose and amino acids.

HIV-I AND HIV-II DOUBLE INFECTION IN CENTRAL AFRICAN REPUBLIC

Certain findings about the HIV-II infection suggest that it is present in the Central African Republic and is not localized to West Africa. The morphology and biological properties of this new virus argue for its classification in the HIV family. HIV-I is endemic in Central Africa including Zaire but HIV-II infection has not been described in this area. Double infection with HIV-I and HIV-II is possible. HIV-I and HIV-II antibodies were sought in sera taken in May 1986 from 82 low-income mothers and in August 1986 from 24 patients of the Bangui Hospital including AIDS and nonAIDS patients. These sera were tested by ELISA with a negative antigen as a control for specificity. By ELISA 14 of the 82 symptomless mothers were positive for HIV-I and among them 11 were also positive by HIV-II ELISA. All were confirmed by western blot as seropositive by HIV-I while only 3 were found positive for HIV-II antibodies. Among the 18 suspected AIDS patients at Bangui Hospital 12 were positive for HIV-I antibodies confirmed by western blot. A 26-year-old woman with suspected AIDS and antibodies to HIV-I and HIV-II died a week after the test; her 6-year-old son was also positive for HIV-I and HIV-II antibodies. None of the 6 nonAIDS inpatients were positive for HIV-I or HIV-II antibodies.

Kinetics of Phenylalanine Disappearance after Intravenous Load in Phenylketonuria and Its Genetic Variants

Summary: Intravenous phenylalanine loading tests were performed in 22 children affected by different types of hyperphenylalaninemia: six cases of classical phenylketonuria (PKU), six cases of atypical PKU, five cases of mild permanent hyperphenylalaninemia, three cases of “transient” PKU, and two cases of the “new variant with progressive neurological illness resistant to dietary treatment,” one of them suffering from DHP reductase deficiency and the other being affected by a defect in biopterin synthesis. A 0.06 M L-phenylalanine (500 ml/m2) solution in NaCl was perfused during 3 hr so that a plasma level of about 2-3 µmol·ml-1 was obtained. Results were compared to those obtained in five controls.In classical, atypical, and mild types, a first order kinetics was observed; the constant of the disappearance rate (k) was, respectively, 2.5, 4.6, and 8.5 X 10-4·min-1, the differences being highly significant (P < 0.001). Expressed as a function of the value of k found in controls (1.37 X 10-2·min-1), these figures represent, respectively, 1.8,2.4, and 6.2% of the normal. A first order kinetics was observed also in the new variant, the values of k (3.5 and 4.4 x 10-4·min-1) being similar to those found in atypical PKU. On the other hand, in the so-called transient PKU, the kinetics of disappearance is a zero-order one. Moreover, the tune course of fall is, on an average, 48 hr, thus demonstrating the persistance of a metabolic disorder in spite of the subnormal plasma levels (0.2–0.3 µmol·ml-1) on a regular diet.The results demonstrate that in the common variants (classical PKU, atypical PKU, and mild forms) the disappearance rate constant of phenylalanine after an intravenous perfusion is proportional to the residual hydroxylase activity as assayed in liver biopsies. They suggest that transient PKU, which is, in fact, a permanent condition, might result from the accumulation of an intermediate, the concentration of which remains constant during the hydroxylation process. Finally, in spite of a normal hydroxylase activity in the in vitro system, an in vivo hydroxylation rate of 3 and 4% of the normal was found in the two children affected by the new variant, which is in good agreement with their daily tolerance and their fasting phenylalanine plasma level on a regular diet.Speculation: The demonstration of a zero-order kinetics of phenylalanine disappearance in transient PKU suggests the accumulation of an intermediate released during the hydroxylation process, which might occur from a phenylalanine hydroxylase-stimulating protein defect.