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Biomedical subjects

A D Patrick

Publications and source records attributed to A D Patrick.

At least 37 records · Page 2Linked to original sources

Prenatal diagnosis of mucopolysaccharidosis by two-dimensional electrophoresis of amniotic fluid glycosaminoglycans.

Amniotic fluid from 72 pregnancies at risk for mucopolysaccharidosis have been analysed for glycosaminoglycans (GAG) by means of two-dimensional electrophoresis. Definite results were obtained in all cases and required only 3 days to report. Of the 66 cases for which GAG analysis was accompanied by enzyme assays on cultured amniotic fluid cells, there was agreement of results in 65. In the one case of disagreement the result of GAG analysis proved to be correct. Fourteen pregnancies were predicted to be affected and the predictions were confirmed by studies on fetal tissues and/or cultured cells, or in one case the birth of an affected infant. Of the 58 pregnancies predicted to be unaffected, 48 have so far gone to term and produced healthy infants. There have been no false negative predictions. The analytical method is simple, rapid, and, in this study, has been found completely reliable to prenatal diagnosis.

Amniotic Fluid↗

Reversal of clinical features of Hurler's disease and biochemical improvement after treatment by bone-marrow transplantation.

A one-year-old boy with type I H mucopolysaccharidosis (Hurler's disease) was given a bone-marrow transplant (BMT) from his mother in an attempt to replace the deficient enzyme, alpha-L-iduronidase (iduronidase). These is definite evidence of engraftment, the enzyme activity of the recipient's leucocytes reaching heterozygote levels within 37 days of the BMT. Graft-versus-host disease (GVHD) developed but was partially controlled by steroids. From 3-4 months after graft until the present (13 months after the graft) iduronidase activity has been present in the serum and the urine and there has been evidence of considerable degradation of glycosaminoglycans excreted in the urine. The hepatosplenomegaly has disappeared, corneal clouding has cleared, and deterioration in the child's development seems to have been arrested.

Aminoacridines↗

Correct prenatal diagnosis of a Hurler fetus where amniotic fluid cell cultures were of maternal origin.

Contamination of amniotic fluid cell cultures by maternal cells can be expected to lead to misdiagnosis of fetal genotype in 0.1 to 0.5/100 cultures, when assays are carried out directly on cultured cells. Chemical analysis of the cell-free amniotic fluid supernatant may overcome this source of error and has the added advantages of speed and independence from amniotic cell culture failure. We describe a pregnancy at risk for Hurler's disease where amniotic cells cultured at amniocentesis had a female karyotype and an alpha-iduronidase activity towards both phenyl and 4-methylumbelliferyl substrates at the lower end of the normal range, suggesting a heterozygous fetus. An affected fetus was predicted, however, because of a high concentration of dermatan sulphate in the amniotic fluid. The discrepancy between these findings was shown to be due to maternal cell contamination of amniotic fluid cell cultures by the birth of a male infant with Hurler's disease.

Amniotic Fluid↗

Acute hereditary tyrosinaemia type I: clinical, biochemical and haematological studies in twins.

Affected twins with acute hereditary tyrosinaemia type I are described. Attempts at therapy with a phenylalanine-tyrosine-methionine restricted diet supplemented with cysteine, vitamin E and ascorbic acid failed to influence the course of the disorder. The bleeding diathesis was due to a morbid reduction of a number of clotting factors, particularly factor VII, and this was associated with impaired platelet aggregation and release. The liver of one showed a marked reduction in fumarylacetoacetate lyase activity and her urine contained a potent inhibitor of red cell delta-aminolaevulinic acid dehydratase. Biochemical investigations of cultured fibroblasts suggest that these do not express the disorder and are unlikely to prove useful diagnostically.

Acetoacetates↗

Axo-dendritic abnormalities in a case of juvenile neuronal storage disease.

Axonal enlargements (meganeurites) and dendritic degeneration were found in the pyramidal neurons from the frontal cortex of a patient with juvenile neuronal storage disease studied with the aid of ultrastructural and Golgi methods. Meganeurites appeared as enlargements at the axon hillock-initial segment area and were similar to those described in other neuronal diseases; dendritic degeneration was heavy and appeared throughout the cell domain. These neuropile changes can be related to the precocious mental abnormalities observed in this group of diseases which depend on a storage phenomenon due to a lysosomal enzyme deficiency.

Adolescent↗

Glutathionuria: gamma-glutamyl transpeptidase deficiency.

A mentally retarded young woman with severe behaviour problems was found to excrete large amounts of glutathione due to a generalized gamma-glutamyl transpeptidase deficiency. As in the only other case described in detail, plasma levels and renal reabsorption of the amino acids were normal. In the parents' urine, plasma and leukocytes, enzyme activity was normal but in their cultured fibroblasts it was below the minimum for the control range. An autosomal recessive mode of inheritance is suggested. The implications of these findings for possible role of the gamma-glutamyl cycle in amino acid transport are briefly discussed.

Adult↗

Expression of hexosaminidase isoenzymes in childhood leukemia.

Because differences in hexosaminidase isoenzyme profiles of granulocytes and lymphoyctes suggested that such profiles might help to distinguish between various types of leukemia, was examined leukocyte extracts from 55 untreated children and 12 controls by automated anion-exchange chromatography. In 23 of 27 cases of the common form of childhood acute lymphoblastic leukemia, the activity of hexosaminidase component I was greatly increased; the activity ratio of hexosaminidase I to hexosaminidase A was greater than 0.5 in 18 of these cases, whereas for other types of leukemia and for all normal cells tested, the ratio was less than 0.2. A raised hexosaminidase I was shown to be associated with leukemic cells by the finding of normal isoenzyme profiles of bone-marrow cells from 17 patients in remission who had such an increase either at diagnosis or in relapse. Hexosaminidase isoenzyme analysis had diagnostic value and may provide a new marker for study of leukocyte differentiation.

Adult↗

Measurement of the alpha-mannosidase activities in human plasma by a differential assay.

A differential assay based on their difference in thermal stability has been used to measure the acidic and true intermediate alpha-mannosidases in the plasma of cntrols and individuals homozygous or heterozygous for mannosidosis. The intermediate activity was found to be independent of age, sex or mannosidosis genotype. The acidic alpha-mannosidase did not vary significantly with age or between sexes for groups of the same age. The concentrations of acidic and intermediate alpha-mannosidase showed a positive correlation for adults but not for children. The ratio of acidic to true intermediate alpha-mannosidase might therefore be a useful secondary test for the detection of adult heterozygotes for mannosidosis.

Adolescent↗

Mannosidosis. Clinical and biochemical study.

The clinical, radiological, and biochemical features of 2 male children with mannosidosis are described. Superficially they appeared to suffer from Hurler's syndrome, but the facies, eye signs, radiological and cytological features were atypical. Excess urinary oligosaccharides were found by thin-layer chromatography. The diagnosis was confirmed by determining the acidic alpha-mannosidase activity of leucocytes and cultured skin fibroblasts. Prenatal diagnosis is possible from cultured amniotic cells.

Adult↗