Search PubMed⌕ Search

Biomedical subjects

L Dallaire

Publications and source records attributed to L Dallaire.

At least 73 records · Page 4Linked to original sources
PubMed1982

Prenatal diagnosis of hereditary tyrosinaemia: measurement of succinylacetone in amniotic fluid.

A method is proposed for prenatal diagnosis in pregnancies at risk of hereditary tryosinaemia. Affected fetuses were detected on the basis of the abnormal presence in the amniotic fluid of succinylacetone, a metabolite previously identified in sera and urines of patients suffering from hereditary tyrosinaemia. Our data show that the forty amniotic control samples had no detectable succinylacetone, while succinylacetone was found in three out of the thirteen cases at risk. Following the parents' decision, these three fetuses were aborted. The ten other mothers who brought their pregnancies to term had normal infants. Enzymatic analysis from two of their aborted fetuses' livers revealed an absence or a low activity of fumarylaceto-acetate hydrolase (EC 3.7.1.2) compared with control fetal livers of the same age.

Amniotic Fluid↗
PubMed1982

Separation of amniotic fluid cell types in primary culture by Percoll density gradient centrifugation.

Amniotic fluid cells obtained by transabdominal amniocentesis at 15-17 weeks of gestation and cultured for 15 and 21 days were separated into three fractions by density gradient centrifugation in Percoll. Each fraction (or peak) corresponded to the following densities: peak A, 1.02-1.03 g/ml; peak B, 1.04-1.05; peak C, 1.05-1.06. Peak A was composed of both non-viable and viable cells; the latter adopted the morphology of epithelial cells in culture. Peak B contained a mixture of fibroblasts and epithelioid cells and peak C had only epithelioid cells. The variability of N-acetyl-beta-hexosaminidase and alkaline phosphatase activities was reduced in peaks B and C as compared to that of peak A and of unseparated cells suggesting that more defined and homogeneous cell types for enzymatic determinations can be obtained by centrifugation in Percoll density gradient. In prenatal diagnosis of biochemical defects, the separation of cells would permit a more precise diagnosis by eliminating enzyme variability due to the presence of different cell types or non-viable cells.

Acetylglucosaminidase↗
PubMed1982

Maternal alphafetoprotein screening by the polypropylene tube immunoradiometric assay on dried blood.

The polypropylene tube immunoradiometric assay for alphafetoprotein (AFP) determination was applied to maternal serum along with a radioimmunoassay technique during the second trimester of pregnancy. Blood from pregnant women was collected by finger prick on strips of chromatography paper (Schleicher and Schuell No. 903C) and air dried. A 4.75 mm disc spot was eluted in anti-AFP coated tubes containing 1.0 ml of assay medium. After one hour the medium was vortexed and the tubes washed and counted on a Concept 4tm (Micromedic Systems, Horsham, PA. 19044). The sensitivity of the technique is about 9 micrograms/l (35 ng/l in the assay) by the Rodbard formula. The concordance between the dried blood and the serum RIA tests in normal pregnancies was over 90 per cent at the 95th and 97th percentiles. This assay on dried blood spotted on chromatography paper was tested on 1003 patients and proved to be an ideal alternative to whole serum screening techniques: it minimizes sample manipulations and can easily be integrated into an existing newborn screening programme.

Female↗
PubMed1982

Oral lecithin and linoleic acid in Friedreich's ataxia: I. Design of the study, material and methods.

A clinical and biochemical evaluation of twenty-two patients with Friedreich's Ataxia and ten normal controls was undertaken in 1980 to assess the effect of lecithin and linoleic acid supplements on the course of the disease. The trial consisted of two consecutive six months periods on either supplements in a double-blind crossover fashion. Clinical appraisal was performed with regards to the following parameters: joints mobility, muscle strength, equilibrium, coordination, motor accuracy, speech and numerous day to day activities. Blood samples were obtained at the beginning and in the course of the trial for enzymatic determinations. This paper describes the methodology of the study.

Administration, Oral↗
PubMed1982

Oral lecithin and linoleic acid in Friedreich's ataxia: II. Clinical results.

Twenty-two patients with Friedreich's Ataxia and ten normal controls were followed for one year and assessed as to their clinical performance after two successive six-month periods of lecithin or safflower oil. Results demonstrated no significant difference in performance scores according to group assignation, neither in patients nor in controls. According to stages, two patients in stage I and to a lesser degree, one patient in stage IV showed better scores for muscle strength and some motor accuracy and coordination tests with lecithin. Controls as groups maintained positive scores in all tests. Patients as groups showed negative mean values in nine out of eleven tests. Again as groups, patients receiving safflower oil demonstrated a mean 8% less deterioration than patients receiving lecithin. This study demonstrates that objective clinical tests and the participation of normal controls are a must in a therapeutic trial implicating patients with a progressive disorder such as Friedreich's Ataxia. The possible role of linoleic acid as the active factor from which clinical improvement proceeded in some specific patients and with early functional stages of the disease, has to be considered and reevaluated in the near future.

Administration, Oral↗
PubMed1982

Oral lecithin and linoleic acid in Friedreich's ataxia: III. Biochemical results.

Lecithin and safflower oil brought about the same changes in serum LAD activity and kinetics in patients with Friedreich's Ataxia as in controls when results of this double-blind crossover study were analyzed according to group assignation. According to functional stages, pretrial LAD activity decreased with advancing severity while Km for lipoamide increased. Lecithin and safflower oil supplements corrected the elevated Km for lipoamide but produced a further reduction in LAD activity. These changes may have been due to the increased intake of linoleic acid, a precursor of lipoic acid, which is present in high percentage in both lecithin and safflower oil. Results of the biochemical study thus agreed with the clinical data gathered during the course of the one-year trial in suggesting that linoleic acid may well have been the active factor through which biochemical and clinical improvement was previously observed in patients with Friedreich's Ataxia supplemented with lecithin.

Administration, Oral↗
PubMed1980

Natural occurrence of a humoral response to Candida in human amniotic fluid.

With a sensitive indirect immunofluorescent technique, we studied the antibody response to Candida albicans in 150 human amniotic fluid (AF) specimens at 15 to 18 weeks' gestation. Specific IgG was detected in 94.7% of the samples and specific IgA, in 98%, while 1.3% were negative in both tests. A comparison of the mean ratio of anticandidal titers (IgA/IgG) in AF and human serum indicated a predominance of IgA activity in AF and the reverse in serum (2.01 versus 0.66, p less than 0.001). There was no correlation between IgG and corresponding IgA titers, which supports the fetal origin of IgA. Humoral immunity alone had no discernible influence on the growth of C. albicans in midtrimester AF. It is suggested that the synthesis of specific IgA is genetically determined because it presumably offers some functional advantage over transmitted maternal IgG in the local defensive mechanisms of the amniotic cavity.

Amniotic Fluid↗
PubMed1980

Correlation between serum lipoamide dehydrogenase activity and phosphatidylcholine therapy in Friedreich's ataxia.

Serum lipoamide dehydrogenase activity and kinetics were studied in nine patients with Friedreich's ataxia before and three months after therapy with oral lecithin. Results disclosed a significant reduction in LAD inhibition by NADH in all patients after therapy. Three patients normalized their increased Km for lipoamide and one patient showed the opposite results after therapy. Two patients ceased lecithin after one month. All seven patients who remained in the trial group and one additional patient, showed subjective and objective signs of improvement in physical resistance. This study has offered some biochemical basis for the apparent clinical improvement in patients with Friedreich's ataxia who undergo lecithin therapy.

Adolescent↗
PubMed1980

The beta-amino acid transport system in Friedreich's ataxia.

Taurine and beta-alanine uptake in cultured skin fibroblasts proceeds through at least two distinct amino acid transport systems. The predominant beta amino acid uptake system which we refer to as the "Beta" system, incorporates taurine in a proportion of 95%. Beta-alanine in a proportion of 80% and does not incorporate beta-amino-isobutyric acid. A second transport system for beta-alanine seems to be operative cultured skin fibroblasts and this system shares the characteristics of system "L" for branched-chain and ring-side neutral amino acids. Results of ion depletion experiments, metabolic inhibition by drugs and blocking agents and previous kinetic studies of taurine and beta-alanine uptake in cultured skin fibroblasts failed to disclose any major difference in beta-amino acid transport between control individuals and patients with Friedreich's ataxia.

Alanine↗
PubMed1980

Origin of amniocentesis-induced rises of alpha-fetoprotein concentrations in maternal serum.

An elevation of alpha-fetoprotein concentration in maternal serum occurred in 7 of 65 patients (11 per cent) following amniocentesis. Analysis of the molecular heterogeneity of the alpha-fetoprotein by chromatography on concanavalin A-agarose indicated that the source of the alpha-fetoprotein was fetal serum in three patients and amniotic fluid in four patients.

Amniocentesis↗
PubMed1980

Alpha-fetoprotein concanavalin A-binding variants in the diagnosis of neural tube defects and other communicating fetal abnormalities.

We have extended our initial observations (Smith et al., 1979) on th use of determining the alpha-fetoprotein (AFP) concanavalin A-binding variant patterns in amniotic fluid for the detection of certain fetal malformations. We report here our complete series of amniotic fluids between 14 and 36 weeks of gestation from 52 normal pregnancies and 28 abnormal pregnancies including anencephaly, open spina bifida, Turner's syndrome, omphalocele, osteogenesis imperfecta congenita, meningomyelocele, meningocele, spinal cysts, spontaneous abortion and fetal death. The percentage of the total amniotic fluid AFP which was not reactive with concanavalin A was significantly lower in the presence of a communicating fetal abnormality (mean = 4.8%, P less than 0.001), one in which the fetal/amniotic fluid barrier is defective, than in the presence of a normal fetus (mean = 24.7%) (or of a noncommunicating fetal abnormality. We applied the concanavalin A-binding assay to two of the above amniotic fluids from pregnancies in progress and correctly classified the gestations as abnormal. Our results indicate that measurement of the percentage of concanavalin A-non-reactive amniotic fluid AFP is a valuable adjunct in the diagnosis of a communicating fetal abnormality, especially when the elevation of amniotic fluid AFP concentration is equivocal (between 2 and 5 S.D. above the mean), when gestational aging is uncertain or when the total amniotic fluid AFP concentration and ultrasonographic data are inconsistent.

Amniotic Fluid↗
PubMed1980

Stunted growth Candida albicans in human amniotic fluid in vitro.

The interaction of human AF with the pathogenic yeast Candida albicans was studied in vitro in 262 samples from early midtrimester and term gestations. Among 111 fluids collected between 15 and 18 weeks, 84% (93) manifested growth-inhibiting activity on 10(2) fungal cells/ml at 24 hr. This phenomenon persisted to a similar extent in late pregnancy. It could not be explained by a lack of nutrients in AF, since the addition of TSB failed to influence the proportion of active fluids. Depletion of the yeast cell glycogen reserve potentiated the degree of fungistasis achieved in several samples (p = 0.0009). Supplementation with either SDB or a physiologic concentration of carbon dioxide effected a complete reversal (p less than 0.0001). Preliminary data as well as overall results suggest that the absolute transferrin content and its pH-dependent saturation with iron are key factors invovled in the growth-inhibiting activity. Germ tube formation was unrestricted in 115 second trimester fluids studied. Human AF probably helps to prevent congenital candidiasis, and this protective function must be better defined.

Amniotic Fluid↗
PubMed1979

Neuraminidase activity in the mucolipidoses (types I, II and III) and the cherry-red spot myoclonus syndrome.

Two neuraminidase (EC 3.2.1.18) comonents, A and B, were distinguished in cultured skin fibroblasts on the basis of thermolability at 37 degrees C. The more labile component (A) t1/2 = 4.7--5.3 min at 37 degrees C, comprises 66--90% of total neuraminidase activity when determined using sodium (4-methylumbelliferyl-alpha-D-N-acetylneuraminate) (MU-alpha-N) as substrate. Activity was assayed at 0 degrees C for 18 h instead of 37 degrees C to fully determine both thermolabile and thermostable components. Diminished activity was noted in cultured fibroblasts from mucolipidoses I, II and III (MLI, MLII, MLIII) and the cherry-red spot myoclonus syndrome (CRSM) patients when assayed at both 0 and 37 degrees C with either MU-alpha-N or each of a series alpha (2 leads to 3)- and alpha (2 leads to 6)-linked N-acetylneuraminyloligosaccharides. Increased sensitivity and rapidity of analyses were achieved using MJ-alpha-N as substrate in determining neuraminidase activity. Results from two obligate heterozygote MLI cell lines (14.5 and 8.0% of control activity) indicate that the MU-alpha-N substrate could be useful for heterozygote detection.

Cells, Cultured↗