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Biomedical subjects

H W Moser

Publications and source records attributed to H W Moser.

At least 145 records · Page 8Linked to original sources
PubMed1991

Low-density particles (W-particles) containing catalase in Zellweger syndrome and normal fibroblasts.

By both histological and biochemical criteria, peroxisomes in patients with Zellweger syndrome appear to be absent or severely deficient. By using 15-30% (wt/vol) Nycodenz/sucrose gradients to study the subcellular localization of extraperoxisomal catalase activity, a commonly used marker for mature peroxisomes, we detected a single peak of activity in Zellweger syndrome fibroblasts at an equilibrium density of 1.13 g/cm3, lower than the expected 1.17 g/cm3 of mature peroxisomes. Upon recentrifugation in either the original gradient or one with a higher salt concentration, essentially all catalase activity was recovered in fractions of the original densities. The activity of the catalase peak was further analyzed by a digitonin titration and filtration assay in combination with Triton X-100 treatment. The catalase activity passed through 0.1-microns and 0.22-microns but was retained on 0.025-microns membrane filters (mean pore size). After treatment with Triton X-100 nearly all catalase activity passed through the filters. The results from fractionations data, digitonin latency measurement, and the detergent effect on the filtration behavior suggest that catalase is not free in the cytosol of Zellweger syndrome fibroblasts as commonly thought but in particles (W-particles). Similar low-density catalase-containing particles, distinct from peroxisomes, are also found in normal fibroblasts. We found that L-alpha-hydroxyacid oxidase, another peroxisomal matrix enzyme, is also present in W-particles derived from normal and Zellweger syndrome fibroblasts. We speculate that the low-density catalase-containing W-particle may represent an immature or incomplete form of peroxisome distinct from previously described "peroxisomal ghosts" in Zellweger syndrome fibroblasts.

Biomarkers↗
PubMed1991

Peroxisomal disorders.

Peroxisomal disorders occur more frequently and have a wider range of clinical manifestations than has been realized in the past. Precise diagnosis can be achieved with non-invasive biochemical assays and all can be diagnosed prenatally, thus providing the option of genetic counseling. Specific therapy is being evaluated for one of these disorders (adrenoleukodystrophy). In addition to these clinical advances, a great deal of information has been gained recently about the biogenesis and normal function of peroxisomes. These latter advances have been stimulated, and in part created, by the study of human disease states. It is for these reasons that a review of these human disease states is relevant for the clinical biochemist.

Amino Acid Sequence↗
PubMed1991

Peroxisomal disorders.

The concept that there are human disease states that are associated with abnormal peroxisomal function is of recent origin. This is due in part to the relatively recent discovery of the organelle itself by de Duve in 1983, and to the earlier belief that it was a vestigial structure in mammals. The recognition that the organelle is significant in mammals was ushered in by Paul Lazarow's observation that rat peroxisomes catalyze the beta-oxidation of fatty acids. By 1981, more than 40 enzymes had been localized to the peroxisome, and the number continues to grow. Respect for the physiological role of the peroxisome in man has been heightened by our recent recognition that peroxisome malfunction causes profound disturbances. The Zellweger cerebro-hepato-renal syndrome represents the most serious peroxisomal disease. It is associated with malfunction of virtually every organ, and children with the disease usually do not survive beyond the 4th month. Application of newly developed diagnostic techniques has shown that the clinical spectrum and frequency of peroxisomal disorders are greater than had been realized. Eleven separate peroxisomal disorders have now been identified. Our laboratory alone has identified more than 2000 patients. Disturbances of very long chain fatty acid and ether phospholipid metabolism are present in 9 of the 11 peroxisomal disorders. In this presentation, we will provide an overview of the peroxisomal disorders, with emphasis on disturbances of fatty acid and ether lipid metabolism.

Adrenoleukodystrophy↗
PubMed1991

Clinical aspects of adrenoleukodystrophy and adrenomyeloneuropathy.

Adrenoleukodystrophy (ALD) is an X-linked recessive disorder that affects mainly the nervous system white matter and the adrenal cortex. It is associated with an abnormal accumulation of saturated very long chain fatty acids and can be diagnosed by demonstrating an excess of these substances in plasma or red cells. Our laboratory has identified more than 900 hemizygotes and 1,000 heterozygotes. Approximately 50% of the hemizygotes have a rapidly progressive childhood or adolescent form of the disease. Twenty-five percent of males have a slowly progressive paraparesis in adulthood, but often are not diagnosed correctly. The illness may also present as Addison disease without apparent neurological involvement. Approximately 15% of heterozygotes develop moderately severe spastic paraparesis. It is important to diagnose ALD promptly because of the urgent need for genetic counseling and the availability of promising therapeutic interventions.

Addison Disease↗
PubMed1991

Photosensitized killing of cultured fibroblasts from patients with peroxisomal disorders due to pyrene fatty acid-mediated ultraviolet damage.

The influence of pyrene-fatty acids on the resistance of cells to ultraviolet (UV) radiation was investigated in cultured fibroblasts from patients with five types of peroxisomal disorders. All showed reduced survival compared to control. The effect varied with the biochemical defect involved and the chain length of the pyrene fatty acid. Reduced survival was observed in cells deficient in plasmalogens (rhizomelic chondrodysplasia punctata) and in cells deficient in peroxisomal fatty acid oxidation (bifunctional enzyme deficiency), which accumulated pyrene-fatty acids. X-linked adrenoleukodystrophy fibroblasts accumulated pyrene-fatty acids and showed increased UV sensitivity only when exposed to longer-chain pyrene fatty acids. UV radiation resistance was lowest in cells with combined impairment of plasmalogen synthesis and fatty acid oxidation (Zellweger syndrome, neonatal adrenoleukodystrophy), suggesting that UV sensitivity correlates inversely with the ratio of plasmalogens to radical producing substances. Fibroblasts deficient in plasmalogens gained normal UV resistance when their plasmalogen levels were normalized by hexadecylglycerol. UV resistance increased when Zellweger cells were fused with X-linked adrenoleukodystrophy cells, and also when Zellweger cells belonging to different complementation groups were fused. The results provide leads to the pathogenesis of the multiple malformations associated with peroxisomal disorders and a method for the selection of cells in which the metabolic defect has been corrected.

Adrenoleukodystrophy↗
PubMed1991

Quantitative magnetic resonance imaging in Rett syndrome.

Rett syndrome (RS) is a progressive neurological disorder of females, characterized by the early onset of autistic behavior, ataxia, and "handwringing" movements. The present magnetic resonance imaging study was undertaken with the purpose of investigating whether structural brain abnormalities of RS patients are similar to those recently reported in autism. The subject population consisted of eight patients and an equal number of age- and sex-matched controls. Area and shape measurements were taken at selected anatomical levels for the following structures: brain hemisphere, corpus callosum, midbrain, pons, lobules I-V and VI-VII of the cerebellum, and head of the caudate. Results revealed significant differences in area for the whole brain hemisphere (p < 0.05) and in both right and left caudate (p < 0.04). These morphological findings are different from those recently reported in autism and emphasize the involvement of the striatal system in RS.

Child↗
PubMed1991

The 22-kD peroxisomal integral membrane protein in Zellweger syndrome--presence, abundance, and association with a peroxisomal thiolase precursor protein.

The primary genetic defect of Zellweger syndrome may be related to defective synthesis or impaired import of peroxisomal proteins. We analyzed the presence and measured the abundance of the 22-kD peroxisomal integral membrane protein (PMP) in patients with Zellweger syndrome. We determined the intracellular localization of the 22-kD PMP and compared it with the localization of a peroxisomal 44-kD thiolase precursor protein. The 22-kD PMP was quantified by immunoblot analyses in liver tissue (n = 7 patients). Immunoblot signals were evaluated using transmission photometry. The intracellular localization of the 22-kD PMP and the peroxisomal 44-kD thiolase precursor protein were determined by immunoblot analyses on fibroblast subcellular fractions prepared by Nycodenz (n = 5 patients) or sucrose density gradient centrifugation (n = 2 patients). The 22-kD PMP was present and associated with membrane fractions in all patients. Its abundance varied in patients as compared with normal human liver controls. The 22-kD PMP was located in subcellular membrane fractions having a lower density than normal peroxisomes or mitochondria. Using two different gradient techniques, the 22-kD PMP and the peroxisomal 44-kD thiolase precursor protein were found in the same low-density gradient fractions. These results suggest that in Zellweger syndrome peroxisome-like elements containing both the 22-kD PMP and a 44-kD thiolase precursor protein are formed. Globally defective synthesis or import of peroxisomal proteins is therefore unlikely to be the primary genetic defect in the patients we studied.

Acetyl-CoA C-Acetyltransferase↗
PubMed1991

Adrenoleukodystrophy.

X-linked adrenoleukodystrophy (ALD) is a disorder of very long chain fatty acid (VLCFA) metabolism that can be diagnosed by demonstrating increased levels of VLCFA in plasma and, prenatally, by similar assays in cultured amniocytes or chorionic vilus samples. ALD causes Addison disease frequently in men and occasionally in women. Prompt diagnosis is important for genetic counseling and for the institution of therapies aimed to prevent or ameliorate the progressive neurologic disability that often is associated with this illness.

Adrenoleukodystrophy↗
PubMed1990

Arachidonic acid metabolism in fibroblasts from patients with peroxisomal diseases: response to interleukin 1.

Prostaglandin E2 synthesis and eicosanoid biosynthetic enzyme activities (arachidonyl CoA synthetase, cyclooxygenase and phospholipase A2) were measured in dermal fibroblasts from patients with metabolic disorders of peroxisomal origin and compared to those from normal subjects and patients with other metabolic disorders of lipid metabolism. Basal- as well as interleukin 1-stimulated prostaglandin E2 syntheses were higher in fibroblasts from patients with X-linked adrenoleukodystrophy, the Zellweger cerebrohepatorenal syndrome and rhizomelic chondrodysplasia punctata than in normals. Basal cyclooxygenase and phospholipase A2 activities were elevated in most of the peroxisomal disease cells. Cells from patients with adrenomyeloneuropathy, however, had significantly lower cytokine-stimulated cyclooxygenase and phospholipase A2 activities than normals, as well as lower prostaglandin E2 synthesis in response to interleukin 1. The peroxisomal disease lines exhibited dose-response curves to interleukin 1 similar to controls. Receptor-binding analysis indicated that cells from patients with rhizomelic chondrodysplasia punctata expressed 5-times fewer interleukin 1 receptors than normals and the other disease lines. Exaggerated arachidonic acid metabolism in response to interleukin 1 suggests that cells from patients with peroxisomal enzyme defects may be useful in elucidating pathways for arachidonate release and eicosanoid synthesis.

Adrenoleukodystrophy↗
PubMed1990

Peroxisomal disorders: complementation analysis using beta-oxidation of very long chain fatty acids.

Complementation studies, using fused cell lines from patients with peroxisomal disorders, have shown correction of defective plasmalogen synthesis and phytanic acid oxidation as well as an increase in the number of peroxisomes. At least six complementation groups have been reported. We demonstrate here that complementing cell lines also acquire the ability to oxidize very long chain fatty acids (VLCFA), and that complementation groups defined with this technique are identical to those reported previously when plasmalogen synthesis was used as the criterion for complementation. This VLCFA complementation technique is of particular value in the study of patients in whom defective VLCFA is the only or major enzymatic defect, and we show complementation between cell lines from two patients each with an isolated defect in one of the peroxisomal fatty acid beta-oxidation enzymes.

Cell Fusion↗
PubMed1990

Peroxisomal disorders.

Although peroxisomes were once considered a vestige, their importance in cellular metabolism is clearly established by the many inherited diseases that have been described in the past two decades. Unfortunately there is no definitive treatment for the various disorders, but based on the recognition of the biochemical abnormalities, prenatal testing and appropriate genetic counseling can be provided. It is essential for clinicians to be aware of this group of diseases, as diagnosis and further study of these patients are essential in understanding the basic etiologic mechanisms underlying these complex groups of disorders. Clearly, there is much to be learned about the relationship between biochemical abnormalities and the phenotypic variability of the peroxisomal disorders.

Brain Diseases, Metabolic↗
PubMed1989

Properties of acid ceramidase from human spleen.

We have characterised ceramidase activity in extracts of human spleen from control subjects and from patients with Gaucher disease. In Triton X-100 extracts of control spleens, a broad pH optimum of pH 3.5-5.0 was found; no ceramidase activity was detectable at neutral or alkaline pH. About 45-60% of acid ceramidase could be extracted from spleen without detergents, but for complete extraction, Triton X-100 was required. For the radiolabelled substrate oleoylsphingosine, a Km of 0.22 +/- 0.09 mM and a Vmax of 57 +/- 11 nmol/h per mg protein was calculated in spleen from a control subject. Flat-bed isoelectric focussing in the presence of Triton X-100 revealed a pI of 6.0-7.0 for acid ceramidase; similar values were found for sphingomyelinase and glucerebrosidase. HPLC-gel filtration indicated that in the presence of Triton X-100, acid ceramidase has an Mr of about 100 kDa. In the absence of detergents, the enzyme forms high-molecular-weight aggregates. Similar aggregation behaviour was observed for sphingomyelinase, while the elution of beta-hexosaminidase was not affected by detergents. The elution profile of glucocerebrosidase was only slightly altered by Triton X-100. There was no difference in the properties of acid ceramidase present in spleen from control subjects and from patients with type I Gaucher disease.

Acid Ceramidase↗
PubMed1989

A case of combined Farber and Sandhoff disease.

We describe a patient with the biochemically established combination of Farber and Sandhoff disease. A 6-month-old girl of consanguineous Turkish parents presented with hoarseness, stridor, scattered skin nodules, painful swelling of hand joints and ankles, and cherry-red macular spots. Until the age of 2 years her motor and physical condition deteriorated distinctly, however her mental state remained unchanged. A biopsied skin nodule disclosed lysosomal inclusions within storage cells that were typical of Farber disease (curved tubular structures). However, other inclusions (e.g. zebra bodies) were also found. Biochemical findings included ceramide accumulation in skin nodules and cultured fibroblasts, impaired ceramide degradation on loading of cultured fibroblasts with radioactive sphingomyelin, profoundly decreased ceramidase activity in fibroblasts as well as total beta-hexosaminidase activity in fibroblasts and serum, absent hexosaminidase A and B bands on cellogel zymograms, increased urinary oligosaccharide excretion of the Sandhoff disease type, and a partial reduction of ceramidase and total beta-hexosaminidase activities in fibroblasts from her father. A diagnosis of combined Farber and Sandhoff disease was made. The effect of both enzyme deficiencies on the clinical manifestations in this patient and the genetic basis of this combination require further studies.

Biopsy↗
PubMed1989

Adrenoleukodystrophy and other peroxisomal disorders that affect the nervous system, including new observations on L-pipecolic acid oxidase in primates.

Impaired nervous system function in childhood is encountered in 10 separate disorders of the peroxisome. Peroxisomal disorders are subdivided into three major groups. In group 1 there is failure to form the organelle and impairment of multiple peroxisomal functions. In group 3 peroxisome structure is intact and the defect involves a single enzyme. In group 2 (rhizomelic chondrodysplasia punctata) peroxisome structure is probably intact, but at least 2 peroxisomal enzymes fail to function normally. We present an overview of this newly recognized field which is so pertinent to brain development. In addition, we present recent and new data about the biochemical defect, genetics and therapy of X-linked adrenoleukodystrophy; about the normal metabolism of L-pipecolic acid in primates and its disturbance in the Zellweger syndrome, and about the prenatal diagnosis of peroxisomal disorders.

Adolescent↗
PubMed1989

Structural and chemical alterations in the cerebral maldevelopment of fetal cerebro-hepato-renal (Zellweger) syndrome.

The cerebra of four abortuses (estimated gestational age 14-22 weeks), diagnosed as cerebro-hepato-renal (Zellweger) syndrome in utero, were examined morphologically with light microscopic, immunocytochemical and ultrastructural techniques and biochemically with gas liquid chromatographic assays for cholesterol ester fatty acids and plasmalogens. Centrosylvian architectonic abnormalities consisting, in part, of thin cortical plates and broad subcortical heterotopic zones were found in all abortuses. Astrocytes, neuroblasts, immature neurons and radial glia contained abnormal pleomorphic cytosomes, presumably of variable lipid composition. The same areas exhibited increases in cholesterol ester very long chain fatty acids and decreased plasmalogens. A pathogenetic hypothesis, proposing that regional tissue constraints act in concert with a peroxisomal-derived biochemical abnormality to impede centrosylvian neuronal migration, is discussed.

Adrenoleukodystrophy↗
PubMed1989

Peroxisomal L-pipecolic acid oxidation is deficient in liver from Zellweger syndrome patients.

L-Pipecolic acid, a cyclic imino acid produced during the degradation of lysine, accumulates in body fluids of infants with the generalized peroxisomal disorders, including Zellweger syndrome, neonatal adrenoleukodystrophy, and infantile Refsum disease. Peroxisome-enriched fractions from normal human liver oxidized L-[3H]pipecolic acid to alpha-[3H]aminoadipic acid (AAA). When human liver organelles were separated on a Percoll gradient, L-[3H]pipecolic acid oxidation activity (as measured by [3H]AAA formation) most closely segregated with the peroxisomal marker, catalase, and was not associated with the mitochondria. L-Pipecolic acid oxidation was not inhibited by antimycin A and rotenone and produced H2O2, consistent with its involving a peroxisomal oxidase. We measured L-pipecolic acid oxidation in liver specimens from patients with peroxisomal disorders. While liver homogenates from adult (n = 5) and infant (n = 10) controls formed 47.1 +/- 6.6 and 48.3 +/- 10.0 pmol AAA/mg protein/h, respectively, Zellweger syndrome livers (n = 8) formed only 1.7 +/- 0.3 pmol AAA/mg protein/h. L-pipecolic acid oxidation in normal infant livers was low at birth and increased with age, but Zellweger syndrome livers showed little activity at any age. Thus, the high circulating levels of L-pipecolic acid in Zellweger syndrome probably result from defective peroxisomal oxidation of L-pipecolic acid to AAA.

2-Aminoadipic Acid↗