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Biomedical subjects

L J Shapiro

Publications and source records attributed to L J Shapiro.

At least 109 records · Page 6Linked to original sources
PubMed1981

Reactivation of an inactive human X chromosome: evidence for X inactivation by DNA methylation.

A mouse-human somatic cell hybrid clone, deficient in hypoxanthine-guanine phosphoribosyltransferase (HPRT) and containing a structurally normal inactive human X chromosome, was isolated. The hybrid cells were treated with 5-azacytidine and tested for the reactivation and expression of human X-linked genes. The frequency of HPRT-positives clones after 5-azacytidine treatment was 1000-fold greater than that observed in untreated hybrid cells. Fourteen independent HPRT-positive clones were isolated and analyzed for the expression of human X markers. Isoelectric focusing showed that the HPRT expressed in these clones is human. One of the 14 clones expressed human glucose-6-phosphate dehydrogenase and another expressed human phosphoglycerate kinase. Since 5-azacytidine treatment results in hypomethylation of DNA, DNA methylation may be a mechanism of human X chromosome inactivation.

Animals↗
PubMed1981

Prenatal diagnosis of Maroteaux-Lamy syndrome.

Maroteaux-Lamy syndrome exhibits deficient activity of the enzyme arylsulfatase-B in cultured skin fibroblasts. Prenatal diagnosis was successfully attempted in two pregnancies of a consanguineous Chaldean couple whose first child is affected with Maroteaux-Lamy syndrome. In both instances, deficient arylsulfatase-B activity was observed in amniotic fluid cell cultures, and the diagnosis was confirmed by 35S-sulfate studies and postmortem enzymology and electron microscopy. The prenatal diagnosis of Maroteaux-Lamy syndrome remains problematic. Residual activity of arylsulfatase-B in the affected homozygote can make interpretation difficult, and the behavior of many lysosomal enzymes varies greatly in response to tissue culture conditions and enzyme extraction processes.

Adult↗
PubMed1981

Increased cholesterol sulfate in plasma and red blood cell membranes of steroid sulfatase deficient patients.

Steroid sulfatase deficiency is an inborn error of metabolism characterized during fetal life by decreased estriol production and postnatally by x-=linked ichthyosis. No consistent substrate abnormalities have been found beyond the perinatal period. Utilizing gas chromatography, we found that the cholesterol sulfate concentration was less than 350 micrograms/100 ml plasma in 9 normal adults, 2 subjects with ichthyosis vulgaris and 2 subjects with lamellar ichthyosis. Control red cell membranes had less than 300 micrograms/100 ml erythrocytes. Eight subjects (age 3 months-74 years) with steroid sulfatase deficiency had strikingly elevated cholesterol sulfate levels with means and ranges as follows: plasma - 3,300 micrograms/100 ml (2,700-4,000), red cell membranes- 7,500 (5,200-9,800) Cholesterol sulfate is known to effect membrane stability and the present observations may help to explain the pathogenesis of STS deficiency and x-linked ichthyosis.

Adult↗
PubMed1981

Cerebroside sulfatase activator deficiency induced metachromatic leukodystrophy.

Two siblings of consanguineous parents had presented with a variety of findings indicative of juvenile metachromatic leukodystrophy (MLD). However, instead of the expected profound deficiency of arylsulfatase A (ARS A), their enzyme levels were about half-normal, and enzyme from fibroblasts had properties identical with the properties of enzyme from normal fibroblasts. Nevertheless, the hydrolysis of cerebroside sulfate by growing fibroblasts was markedly attenuated. Supplementation of the fibroblasts with cerebroside sulfatase activator normalized the response in the loading test. These results imply that the fibroblasts, and by extension the patients, are deficient in activator. Although the defective catabolism of cerebroside sulfate and the clinical manifestations in these patients mimic MLD, the molecular basis is distinct from the classical forms of the disorder.

Cerebroside-Sulfatase↗
PubMed1980

Serum pyruvate-kinase (PK) and creatine-phosphokinase (CPK) in female relatives and patients with X-linked muscular dystrophies (Duchenne and Becker).

Determination of serum creatine phosphokinase (CPK) activity is often used in efforts to detect carriers of X-linked muscular dystrophies. We have recently demonstrated that another serum enzyme, pyruvate-kinase (PK) may also be of use in the diagnosis of patients affected with a variety of neuromuscular disorders. To evaluate the usefulness of this assay for carrier detection, a comparative study of serum PK and CPK activity was performed in 74 female relatives of patients affected with Duchenne (DMD) and Becker (BMD) muscular dystrophies. For obligate carriers of the DMD gene, 10 of 14 had elevated CPK's, 11 of 14 had elevated PK's and 12 of 14 had abnormal results for either of the two enzymes. Three of 16 mothers of isolated cases had increased serum CPK activity and 6 of 16 had increased PK activity (7 had elevation of at least one enzyme). These preliminary data suggest that the use of PK may enhance the capability to discriminate carriers for these X-linked recessive genes.

Adolescent↗
PubMed1980

Expression of an X-linked gene from an inactive human X chromosome in mouse-human hybrid cells: further evidence for the noninactivation of the steroid sulfatase locus in man.

Somatic cell hybrid clones were derived from the fusion of hypoxanthine phosphoribosyltransferase (HPRT; EC 2.4.2.8)-deficient mouse cells and two different human fibroblast strains, each carrying an X chromosome-autosome translocation. One of these had an X/11 translocation [46,X,t(X;11)(p21;q13)] and the other had an X/19 translocation [46,X,t(X;19)(q22;q13)]. The structurally normal human X chromosome is the late-replicating (genetically inactive) chromosome in these two cell strains; the rearranged X chromosome is early replicating (genetically active). One primary hybrid clone carrying both the translocated X chromosome and the structurally normal X chromosome was isolated in hypoxanthine/aminopterin/thymidine medium from each of these two cell fusion experiments. These clones were then selected in medium containing 8-azaguanine to achieve the loss of the active human HPRT locus. Five subclones from the cell hybrid with the X/11 translocation failed to express two known human X-chromosome markers [glucose-6-phosphate dehydrogenase (G6PD; EC 1.1.1.49) and phosphoglycerate kinase (PGK; EC 2.7.2.3)] but did express human microsomal steroid sulfatase (STS; sterol-sulfate sulfohydrolase, EC 3.1.6.2). Three of these were cytogenetically analyzed and found to contain a structurally normal human X chromosome but not the X/11 translocation. Two subclones were isolated in 8-azaguanine from the hybrid with the X/19 translocation. Cytogenetic analysis of these two clones showed the presence of a structurally normal human X chromosome; the X/19 translocation was not present. They did not express human G6PD, PGK, or HPRT but did express human STS. These results indicate that human STS is expressed from a locus on the inactive human X chromosome and support our earlier finding that the STS locus escapes X-inactivation in man.

Animals↗
PubMed1979

Non-inactivation of an x-chromosome locus in man.

Cloned fibroblasts from women heterozygous for X-linked ichthyosis (steroid sulfatase deficiency) were examined to see whether or not this locus is subject to X-inactivation. Of 103 clones examined, all had normal levels of steroid sulfatase activity. Two of the women studied were also heterozygous for glucose-6-phosphate dehydrogenase deficiency. This allowed the demonstration that both X chromosomes were represented as the active X in various clones and that selection did not account for these findings. Thus, the steroid sulfatase locus, like the Xga locus to which it is linked, appears to escape X-inactivation in man.

Dehydroepiandrosterone↗
PubMed1979

Regional assignment of the steroid sulfatase-X-linked ichthyosis locus: implications for a noninactivated region on the short arm of human X chromosome.

The expression of steroid sulfatase (SS; sterol-sulfatase; sterol-sulfate sulfohydrolase, EC 3.1.6.2), a microsomal enzyme that catalyzes the hydrolysis of a variety of 3beta-hydroxysteroid sulfates, was evaluated in mouse-human hybrid clones. The mouse parental line, A9, was found to have little SS as determined by activity measurements. Human SS can be separated from mouse SS by electrophoresis. Two human fibroblast lines, one carrying an X/13 translocation [46,X,t(X;13)(p22;q12)] and the other carrying an X/20 translocation [46,X,t(X;20)(Xp20q;Xq20p)] were used as the human parental lines. Several independently derived hybrid clones from each of the two fusion experiments were analyzed for the expression of human SS by activity measurements and electrophoresis. Cytogenetic analyses were done on these hybrid clones at the same passage level. The results showed that the expression of human SS in these cell hybrids was concordant only with the presence of the distal half (p22-->pter) of the short arm of the human X chromosome, thus assigning the locus for SS to Xp22-->Xpter. Earlier studies have shown that the deficiency of SS is the basis for the dermatologic condition X-linked ichthyosis, the gene for which is known to be located approximately 10 centimorgans from the Xg blood group locus. The localization of SS on the X chromosome indicates that Xg locus may be on the short arm of X and possibly on its distal half. The Xg locus is thought to escape X-inactivation in man, and recent investigations suggest that the SS locus also escapes X-inactivation. Our results thus provide evidence for the location of an apparently noninactivated site on the distal half of the short arm of the human X-chromosome that contains the locus for SS and possibly the Xg locus.

Chromosome Mapping↗
PubMed1979

Metachromatic leukodystrophy without arylsulfatase A deficiency.

Two siblings of consanguinous parents were noted to have a neurologic syndrome marked by developmental delay, regression of psychomotor performance, marked spasticity and progressive central nervous system degeneration. Markedly delayed nerve conduction times and a sural nerve biopsy which demonstrated changes typical of metachromatic leukodystrophy (MLD) were evident. Impairment of sulfated glycolipid metabolism was documented by analysis of glycospingolipid in urinary sediment. In spite of these findings, activities of arylsulfatase A and cerebroside sulfatidase in white blood cells and cultured skin fibroblasts were near normal. However, when intact growing fibroblasts were loaded with 35SO4-sulfatide a clear defect in sulfatide cleavage, comparable to that seen in MLD patients, was observed. Thus, these patients represent a new form of sulfatide storage disease -- MLD characterized by intact enzyme activity in cell homogenates but defective sulfolipid metabolism in vivo and in intact fibroblasts.

Adult↗
PubMed1979

Arysulfatase A modulation with pH in multiple sulfatase deficiency disorder fibroblasts.

It has been observed that multiple sulfatase deficiency disorder (MSDD) fibroblasts contained from profoundly deficient to near normal amounts of arylsulfatase (ARS) A depending on the medium in which they were cultured. Our present findings show that the major factor determining the enzyme level is the pH of the medium during growth. In media which became acidic or was maintained at low pH (less than 7), the cells expressed the enzymopathy, while in high pH media (7.4), the cells produced enzyme. The high and low enzyme states were reversible. The ARS A deficiency in MSDD must, therefore, be a secondary manifestation of a mutation in another system.

Cerebroside-Sulfatase↗
PubMed1979

Estimating sex ratio biases in X-linked disorders: is there an excess of males in families with X-linked ichthyosis?

We derive the conditional probabilities for estimating the sex ratio in families ascertained through affected males for the study of X-linked recessive diseases. These conditional probabilities correct for the fact that the probability that a family will be ascertained increases with the number of males in the family. Data from four published studies for X-linked ichthyosis vulgaris are analyzed, three having an excess of males and one having a highly statistically significant excess of males. It is not known if this difference in the two samples represents a biological difference between the two populations or an unrecognized ascertainment bias.

Female↗
PubMed1978

Enzymatic basis of typical X-linked icthyosis.

Steroid sulphatase activity was determined in cultured fibroblasts from 25 individuals with X-linked ichthyosis from four countries. All those with X-linked disease had markedly reduced enzyme levels compared with controls and patients with other types of ichthyosis. X-linked ichthyosis seems to be the result of a common mutation affecting the expression of steroid-sulphatase activity.

Adult↗
PubMed1978

X-linked ichthyosis due to steroid-sulphatase deficiency.

An assay of cultured skin fibroblasts identified several individuals with 3 beta-hydroxysteroid-sulphate sulphatase deficiency. All patients with this inborn error of metabolism had clinically apparent ichthyosis and a family history of this skin disorder compatible with X-linked inheritance. It is concluded that steroid-sulphatase deficiency is the bio-chemical basis of at least some cases of X-linked ichthyosis.

Adult↗
PubMed1978

Serum pyruvate-kinase (PK) and creatine-phosphokinase (CPK) in progressive muscular dystrophies.

PK and CPK have been determined in the serum from 208 individuals including 70 normal controls (61 adults and 9 children) and 138 patients with a variety of neuromuscular disorders. In adult controls the mean activity (+/- SE) for PK is 1.2 +/- 0.05 mumol/ml/h. In normal children PK activity was about twice as high as in normal adults and decreases with increasing age. In 26 patients with Duchenne dystrophy the range of serum PK was 4.0-150.4 and in 17 individuals with the Becker type, 3.0 to 148.7. All had elevated PK and CPK levels. Eighteen of 20 patients with the facio-scapulo-humeral (FSH) from of muscular dystrophy had increased PK while only 9 had elevated CPK. Regression analyses have shown an inverse correlation between PK levels and age (or degree of disability in DMD). Kinetic and electrophoretic studies indicate that the PK isozyme found in the serum from affected patients and from heterozygotes for the DMD gene is mainly the M1 type PK, which is the only PK isozyme found in skeletal muscle and brain and the major component from myocardium.

Adolescent↗