New amphibian models for the study of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)

We report the development of two animal models in amphibians (frogs and salamanders) in whom 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) produces the behavioral (neurological) and biochemical equivalents of the human disease and, in addition, a measurable modification in at least one form of pigment-bearing cell from the neural crest, the skin melanocyte. We propose that this new approach can become an inexpensive, easily quantifiable model for the study of the effect of MPTP on the central and peripheral nervous systems. We also demonstrate that the toxic effect of MPTP can be completely abolished in vivo by treatment with a monoamine oxidase inhibitor and potentiated by an inhibitor of catechol-O-methyltransferase. MPTP is catabolised by oxidation into toxic metabolites, but 1-methyl-4-phenylpyridinium ion (MPP+), the proposed end-metabolite, is even more toxic than MPTP in this model, possibly through a different mechanism.

[Comparison of the metabolic response of the premature child fed parenterally, and then with mother's milk of prematurity]

The nitrogen retention and plasma amino acid concentration were determined in eight preterm infants (mean birth weight 970 +/- 130 g; mean gestational age 28 +/- 1 weeks) receiving successively total parenteral nutrition and their own mother's milk. The nitrogen retention during both regimens was comparable to the fetal accretion rate. Plasma amino acid concentrations were lower during the enteral phase of the study than during parenteral nutrition. The metabolic response of small preterm infants is related to the quality of amino acids as well as to the route of intake.

Oral and dental development in X chromosome aneuploidy

Though frequently noted, orofacial anomalies in poly X syndromes have been seldom reviewed. In a study of patients with an X chromosome aneuploidy (XXXXX, XXXX, XXXXY, XXXY) the following facial and dental defects were found to be characteristic features of these syndromes: mainly bifid uvula and macroglossia, enamel defects, dental taurodontism and abnormal roots. These observations are discussed in the light of the possible role of X-linked genes.

Effect of amino acid composition of parenteral solutions on nitrogen retention and metabolic response in very-low-birth weight infants

To evaluate the influence of amino acid preparations on the metabolic response of parenterally fed immature newborn infants, nitrogen retention and plasma amino acid concentrations were compared in very-low-birth-weight infants given two parenteral regimens differing only by the composition of the infused amino acids (Travasol 10% blend B and Vamin 7%). The intakes of fluid, nitrogen, and calories were comparable. The nitrogen retention was 72% +/- 7% with Vamin and 65% +/- 6% with Travasol. The differences in plasma amino acid concentrations were consistent with the composition of the amino acid solutions. During the infusion of Vamin the increased intake of aromatic amino acids resulted in high plasma levels of tyrosine (256 +/- 233 mumol/L, range 67 to 894 mumol/L). The infusion of Travasol resulted in high plasma levels of methionine (114 +/- 39 mumol/L, range 53 to 260 mumol/L) and an elevated load of glycine, which was accompanied by an abnormally high urinary loss of this amino acid. Despite these metabolic imbalances, the growth rate over the whole study was adequate. These results emphasize the importance of the composition of amino acid solutions on the metabolic response of the very immature preterm infant.

The composition of preterm milk in relation to the degree of prematurity

Fifty-one samples of 24-h milk collections obtained during the 1st month of lactation from mothers who delivered after gestations of 26 to 31 wk (VPT) contained higher concentrations of nitrogen (297 +/- 11 mg/dl), total fatty acids (4.46 +/- 0.17 g/dl), percentage medium chain fatty acids (10.8 +/- 0.7), and energy (78.3 +/- 2.0 kcal/dl) than either or both those from 32 to 36 wk (PT) and term (T) gestations. PT collections did not differ from T milk with regard to nitrogen (250 +/- 13 versus 259 +/- 13), total fatty acids (3.94 +/- 0.20 versus 3.20 +/- 0.30), percentage medium chain fatty acids (9.1 +/- 0.5 versus 8.1 +/- 0.7) and energy (69.0 +/- 2.7 versus 66.6 +/- 2.4). Although postpartum age (5 to 10 versus 11 to 30 days) did not change the nutrient and energy content of VPT, PT, and T collections, it is only in 11 to 30 day VPT milk that nitrogen and energy content became higher (p less than 0.05) than either or both PT and T milk. We conclude that the differences in macronutrient composition of PT milk are limited to VPT milk and the data from repeated milk collections in the same mother (28 wk) suggest that there is considerable variability in its composition.

Friedreich's ataxia: malic enzyme activity in cellular fractions of cultured skin fibroblasts

We have measured the activity of malic enzyme NADP+ dependent in the nuclear, mitochondrial, lysosomal and cytosolic fractions of cultured skin fibroblasts from twelve patients with Friedreich's ataxia and nine control subjects. Hexosaminidase, cytochrome-C-oxidase, lactate dehydrogenase and malic enzyme NAD+ dependent were used as marker enzymes. The activity of malic enzyme NADP+ dependent was not significantly reduced in the mitochondrial fraction of patients with Friedreich's ataxia as compared with controls. When corrected for possible contamination between mitochondrial and cytosolic fractions, malic enzyme NADP+ dependent activity was still not significantly reduced in patients with Friedreich's ataxia. Unless critical methodological differences were overlooked in this or previously published studies, we conclude that mitochondrial malic enzyme deficiency is not the primary genetic defect underlying Friedreich's ataxia.

Date of conception and prevention of neural tube defects

The authors studied the time of conception of 280 fetuses and liveborns with anencephaly or spina bifida seen in a French Canadian population during a period of six years. There is an evident seasonal variation in the conception of NTD fetuses. Using a wave statistical model applied to data recorded over a six year period the authors have rejected the "no variation between the six two-month intervals" hypothesis at a P less than or equal to 0.005 level. It is postulated that, in any vitamin intake or environmental program to prevent NTD in families at risk, one must take into account the annual and seasonal variations, ethnic groups identity and the date of conception in the choice of control mothers.

Prenatal detection of the congenital nephrotic syndrome (Finnish type) by trehalase assay in amniotic fluid

We report relatively high trehalase activity in the amniotic fluid of two fetuses affected with the congenital nephrotic syndrome of the Finnish type. The results suggest that prenatal detection of this condition can be done on this basis in conjunction with the alpha-fetoprotein and acetylcholinesterase tests in amniotic fluid.

Differential stabilities of fetal intestinal disaccharidases determine their relative amounts released into amniotic fluid

Comparison of relative disaccharidase activities in jejunal mucosa, amniotic fluid, and meconium samples taken from the ileum, proximal and distal colon of 5 human fetuses, indicates that trehalase and lactase are more sensitive to the denaturation conditions existing in the fetal intestinal lumen than maltase, sucrase, palatinase and turanase . Relative activities of sensitive disaccharidases (trehalase and lactase) were also low in the amniotic fluid of these fetuses as compared to the jejunal mucosa. These results suggest that the in vivo stability of disaccharidases, exposed to proteolytic digestion and other denaturing conditions in the fetal intestinal lumen, governs the relative activities of these enzymes released into the amniotic fluid.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Prenatal detection of intestinal obstruction: deficient amniotic fluid disaccharidases in affected fetuses

Amniotic fluid samples from four fetuses with intestinal obstructions (two anal imperforations, one duodenal atresia and one multiple intestinal atresia) were deficient in disaccharidase activities. These results indicate that disaccharidase assay in amniotic fluid can be used as a rapid and simple test for the prenatal detection of fetal intestinal obstructions.

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.

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.

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.

Viability assessment by dye exclusion. A fluorescent method for fungal cells

A new fluorescent staining technique for fungi utilizes the differential affinity of dead cells for rhodamine B. A mounting medium has been devised that includes the dye. This medium allows direct processing of cells from a broth and provides optimal conditions for fluorescence intensity. Comparison with the standard methylene blue exclusion test as applied to the Candida albicans yeast phase indicates similar specificity. Various pseudohyphae and several fungi also exhibited selective uptake of the dye when killed. This technique should prove useful in studying the effect of both drugs and cells on pathogenic yeasts.

Origin and developmental patterns of lactase and other glycosidases in sheep amniotic and allantoic fluid

Intestinal lactase activity (with its associated cellobiase, 4-methylumbelliferyl-beta-galactosidase and -beta-glucosidase activities) was used as a specific intestinal marker enzyme to study the release of protein and enzymes of intestinal origin in sheep amniotic fluid during gestation. In amniotic fluid, intestinal lactase activity peaked at 66--85 days of gestation and then decreased with gestation. This enzyme activity was very low or absent in allantoic fluid throughout gestation suggesting that there is no important transfer of amniotic fluid lactase towards the allantoic cavity. Maltase and 4-methylumbelliferyl-alpha-glucosidase showed no statistically significant variation with gestation in both amniotic and allantoic fluid whereas alpha-galactosidase and N-acetyl-beta-hexosaminidase which were first higher in allantoic than in amniotic fluid increased in amniotic fluid to reach allantoic fluid levels near term. Such patterns are consistent with the suggestion that the fetal urine is a source of alpha-galactosidase and N-acety-beta-hexosaminidase activities and that sheep urine is first accumulated in the allantoic sac via the urachus up to 86--90 days of gestation and thereafter passes more and more into the amniotic sac.

Dicarboxylic amino acid uptake in normal, Friedreich's ataxia, and dicarboxylic aminoaciduria fibroblasts

Glutamic and aspartic acid uptake was measured in skin fibroblasts from patients with Friedreich's Ataxia, dicarboxylic aminoaciduria, and normal individuals. The results showed no difference in uptake kinetics of either dicarboxylic amino acids between Friedreich's Ataxia and normal cells, but reduced uptake velocities in dicarboxylic aminoaciduria fibroblasts. Friedreich's Ataxia fibroblasts were, however, less calcium-dependent and more magnesium and phosphate-dependent than controls in glucose-free incubation mixture. This difference might be related to some degree of glucose intolerance by Friedreich's Ataxia fibroblasts in culture.

Pyruvate dehydrogenase, lipoamide dehydrogenase and citrate synthase activity in fibroblasts from patients with Friedreich's and Charlevoix-Saguenay ataxia

The activity of lipoamide dehydrogenase and two closely related enzymes was studied simultaneously in early, mild, and late passage fibroblast cultures. Friedreich's ataxia fibroblasts tended to lose pyruvate dehydrogenase and citrate synthase activities, while lipoamide dehydrogenase activity remained constant with aging of the cells. Mean pyruvate dehydrogenase activity was lower over-all in fibroblasts from ataxics. Mean citrate synthase activity was higher in ataxic fibroblasts. Present tissue culture media do not represent the best conditions in which to reproduce cofactor binding defects such as those found in other genetic diseases with structural enzyme mutations.

Taurine and beta-alanine uptake in cultured human skin fibroblasts from patients with Friedreich's ataxia

Taurine and beta-alanine uptake kinetics were studied in cultured skin fibroblasts from 9 patients with Friedreich's Ataxia and 8 controls. No significant difference was observed. The data support the presence of normal beta-amino acid carrier protein in Friedreich's Ataxia cell membrane.

Reactivity of amniotic fluid alpha-fetoprotein with concanavallin A in diagnosis of neural tube defects

Alpha-fetoprotein (AFP) concanavallin-A-affinity molecular variant patterns were determined in amniotic fluid samples from 10 pregnancies complicated by anencephaly (6), spina bifida (1), Turner's syndrome (1), osteogenesis imperfecta congenita (1), and fetal death (1) and 20 normal pregnancies between 14.6 and 25.5 weeks of gestation. With the exception of one anencephalic pregnancy, the AFP concentrations in samples from women with a fetal abnormality were more than 5 SD above normal for gestational age. In every case, however, the proportion of total amniotic fluid AFP that was not reactive with concanavallin A was significantly smaller in the presence of a fetal abnormality (mean 2%) than when the fetus was normal (mean 20%). The results suggest that measuring the amount of concanavallin-A-non-reactive amniotic fluid AFP will be a valuable test for diagnosing fetal abnormality, especially when an increase in total amniotic fluid AFP concentration is equivocal or gestational age is uncertain.

Antenatal diagnosis of neural tube defects in Canada: extension of a collaborative study

Experience with the diagnosis of neural tube defects from alpha1-fetoprotein (AFP) concentrations in amniotic fluid is reported from a prospective study of five laboratories testing for 13 Canadian genetic centres. The results of the study indicate that antenatal diagnosis of open neural tube defects is being carried out effectively in Canada (in 99.2% of cases the AFP measurements were interpreted correctly). Amniocentesis should be recommended to women at high risk for having a child with a neural tube defect (i.e., those who have a child, a parent or a sibling with a neural tube defect). The rate of neural tube defects in 182 high-risk pregnancies was 2.2% for an open defect and 1.1% for a closed defect, whereas the rate in 673 pregnancies in which amniocentesis was being performed for other reasons was 0.3%. This suggests that the AFP concentration should be measured in any sample of amniotic fluid collected for other reasons (usually fetal karyotyping). There were three instances of false-negative results, for a rate of 0.4%. Two closed neural tube defects were not detected; this limitation of the test has also been found by others. One of the six fetuses with an open neural tube defect, who died in utero, had a large myelocele in the neck that was not recognized. There were also four instances of false-positive results, for a rate of 0.5%. The findings suggest that AFP values that are more than 2 but less than 7 standard deviations (SDs) above the mean may indicate a neural tube defect, and that values 7 or more SDs above the mean very likely indicate such a defect, although other reasons for such high values (e.g., fetal erythrocytes in the amniotic fluid, intrauterine death and mistaken gestational age) must be ruled out by other methods.

Purification and some properties of liver and brain beta-N-acetyl-hexosaminidase S

beta-N-Acetyl-hexosaminidase S (2-acetamido-2-deoxy-beta-hexoside acetamido-deoxyhexohydrolase, EC 3.2.1.52) was purified from liver and brain of a patient deceased of type O GM2 gangliosidosis (Sandhoff's disease). Brain beta-N-acetyl-hexosaminidase S was further purified by preparative polyacrylamide gel electrophoresis. The pH optimum of the purified liver and brain enzyme was 5.0 and Km values were 0.8--0.9 mM and 0.3--0.4 mM with 4-methylumbelliferyl-beta-D-N-acetylglucosamine and beta-D-N-acetylgalactosaminide derivatives, respectively. beta-N-Acetyl-hexosaminidase S was thermolabile losing most of its activity after 50 min at 50 degrees C. The apparent molecular weights of the purified liver and brain enzymes were 154 000 and 152 000, respectively. Hexosamines activated beta-N-acetyl-hexosaminidase S whereas the isoenzyme A and B were inhibited. The glycoprotein nature of beta-N-acetyl-hexosaminidase S was suggested by its affinity towards Concanavalin A-Sepharose.

Neuraminidase in cultured fibroblasts and leucocytes of homozygotes and heterozygotes for the mucolipidosis II gene (I-cell disease)

The significance of neuraminidase deficiency reported to be the primary defect in mucolipidosis II has been evaluated by determination of this enzyme activity in cultured fibroblasts, culture medium, and leucocytes from homozygote and heterozygous carriers of the disease. A new and sensitive fluorometric assay of neuraminidase was used with sodium (4-methylumbeliferyl-alpha-D-N-acetylneuraminate) as substrate. We report: 1) nearly total deficiency of neuraminidase in mucolipidosis fibroblasts, 2) partial deficiency of this enzyme in leucocytes of one patient, 3) this decreased activity ceases to exist following Triton X-100 treatment, and 4) intermediary mean neuraminidase activity in fibroblasts and leucocytes from obligate heterozygotes. Although these results would be consistent with the suggestion that neuraminidase deficiency is the primary defect in this disease, evidence from the work of other authors suggests that the enzyme deficiency results from a secondary effect of the mucolipidosis II mutation.

Confirmation of regional assignment of nucleoside phosphorylase (NP) on chromosome 14 by gene dosage studies

Gene dosage studies yielded results consistent with assignment of the locus for nucleoside phosphorylase to band 14q13. The red blood cells from a patient with the karyotype 47,XX,+der(14),t(8;14)(8qter leads to 8q24::14q21 leads to 14pter)pat had enzyme activity 50% higher than red cells from 47 normal controls, two trisomies involving chromosomes other than 14, and five balanced translocations involving chromosome 14. On the other hand, the red cells of a case with a karyotype 45,XX,-14,-22+der(22),t(14;22)(14qter leads to 14q11 or 14q12::22p11 leads to 22qter)mat and a case with a a karyotype 47,XX,+der(14),t(14;16)(14pter leads to 14q11::16q24 leads to 16qter)mat had normal activity

Lipoamide dehydrogenase in cultured human skin fibroblasts

Lipoamide dehydrogenase was identified in cultured skin fibroblasts of normal individuals and patients with Friedreich's ataxia. The optimum conditions for its assay were defined. Data disclosed a normal range of 36--122 mumol/min/mg protein in control fibroblasts and 61--112 mumol/min/mg protein in patients fibroblasts. Numerous precautions should be taken in handling fibroblast cultures for lipoamide dehydrogenase determination.

Developmental patterns of intestinal disaccharidases in human amniotic fluid

A close relationship exists between relative disaccharidase activities (maltase, sucrase, trehalase, palatinase, turanase, lactase, and cellobiase) in amniotic fluid and corresponding jejunal mucosa of five human fetuses (16 to 21 weeks of gestation) suggesting that these intestinal enzymes pass into amniotic fluid. Serial determination of disaccharidase activities in amniotic fluid samples collected between 10 and 42 weeks of gestation showed maximum mean activities at 14 to 17 weeks of gestation and a rapid drop to less than 12 per cent maximum values at about 22 weeks. This drop is probably caused by combined effects of decreased extrusion rate of intestinal disaccharidases and increased reabsorption of the enzymes in swallowed amniotic fluid with fetal development.

Lipoamide dehydrogenase in Friedreich's ataxia fibroblasts

Lipoamide dehydrogenase was measured in cultivated skin fibroblasts from twelve patients with Friedreich's ataxia and nine normal controls. No difference in specific activity, subcellular distribution and Vmax or Km was observed between patients and controls.

Dicarboxylic aminoaciduria: an inborn error of amino acid conservation

A 38-month-old apparently healthy male has been followed for three years because of a massive glutamic and aspartic aminoaciduria detected shortly after birth in a neonatal screening program. Amino acid clearance studies revealed the presence of renal wastage of dicarboxylic amino acids. Intestinal transport and in vitro oxidation of dicarboxylic amino acids were found to be intact. Clinical and metabolic data obtained on a previously described patient and the present case suggest that some patients with dicarboxylic aminoaciduria might have a selective renal conservation defect without clinical abnormalities, whereas others might demonstrate an additional defect in intestinal transport associated with fasting hypoglycemia.

N-Acetyl-beta-hexosaminidase isoenzymes of amniotic fluid and maternal serum. Their relevance to prenatal diagnosis of the GM2 gangliosidoses

The isoenzymes of N-acetyl-beta-hexosaminidase were quantitated in 30 amniotic fluid and 13 maternal serum samples collected between 11 and 40 weeks of gestation using DEAE-Sephadex A-25 chromatography. Isoenzymes A and B consitituted the major components of most amniotic fluids but seven samples characterized by high N-acetyl-beta-hexosaminidase activities contained high proportion of an isoenzyme apparently identical to isoenzyme P of maternal serum. This passage of maternal serum N-acetyl-beta-hexosaminidase into the amniotic cavity could lead to false negative diagnosis of type B and type O GM2 gangliosidoses if the diagnosis rely solely upon isoenzyme analysis in amniotic fluid. However, the release of maternal enzyme into amniotic fluid seems to be restricted to the third trimester of gestation and should not interfere with prenatal diagnosis of the GM2 gangliosidoses ususally performed at an earlier stage of gestation.

Prenatal diagnosis of genetic disease in Canada: report of a collaborative study

A study of 1223 amniocenteses carried out during 1020 pregnancies in 990 women showed that 2nd-trimester amniocentesis at about 16 weeks' gestation is a safe, accurate and reliable procedure for the diagnosis of certain classes of genetic disease when it is monitored by ultrasound, performed by a trained obstetrician and carried out in a major health sciences centre. The percentage of fetal losses (4.7%) and neonatal deaths (0.5%) during the study was not greater than in control samples for women 35 years of age and older. The best results were obtained when needles of gauge 20 or 21 were used. The use of needles of gauge 19 or larger and more than two insertions during a single amniocentesis were associated with a significantly greater frequency of fetal loss than a second or even a third amniocentesis during the same pregnancy. For 39 fetuses (3.8%) a diagnosis of a genetic abnormality was made and 23 male fetuses were found to be potentially hemizygous for an X-linked gene. There were 51 therapeutic abortions as a result of the diagnosis. Sixty-six tests (5.4%) gave an inconclusive result and seven (0.6%) gave an erroneous diagnosis; five of the latter (two false-positives and three false-negatives) resulted from the alpha1-fetoprotein test for neural-tube defects and in two cases the sex was incorrectly determined. The frequency of all chromosome abnormalities was 1:20 when the mother's age was 40 years or more and 1:60 when the mother's age was between 35 and 39 years. When a mother had previously had a child with a chromosome abnormality the risk of recurrence of such an abnormality was 1:100 when the age of the mother was 35 years or more.

A syndrome of generalized elastic fiber deficiency with leprechaunoid features: a distinct genetic disease with an autosomal recessive mode of inheritance

Three male infants with generalized elastolysis and leprechaunoid features from two related and consanguineous parents of Italian origin died in the first year of life following severe cardio-pulmonary complications. While these children showed a decrease in elastic fibers, no degeneration was noted and histochemical as well as systemic metabolic studies were negative. It is postulated that this disease is a variant of cutis laxa or at least that the absence of granular degeneration of the elastic fibers described by Goltz is a secondary manifestation present only in older children. Prenatal diagnosis of this syndrome is not yet possible since no intracellular or biochemical changes have been identified. In view of the familial occurrence of this syndrome, and the association of specific clinical and pathological findings, we suggest that we are dealing with a distinct hereditary disorder of the connective tissue.