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At least 631 records · Page 35Linked to original sources
PubMed2002

Deficiency of epidermal protein-bound omega-hydroxyceramides in atopic dermatitis.

Atopic dermatitis is a common skin disease of unknown etiology with an impaired permeability barrier function. To learn more about the molecular pathology in lesional skin, we analyzed levels of free extractable as well as protein-bound barrier lipids in the epidermis of atopic dermatitis subjects. The amount of protein-bound omega-hydroxyceramides in healthy epidermis comprised 46-53 wt% of total protein-bound lipids, whereas this percentage was decreased to 23-28 wt% in nonlesional areas and even down to 10-25 wt% in affected atopic skin areas of the subjects. Furthermore, the partial amount of free extractable very long chain fatty acids with more than 24 carbon atoms was reduced in affected regions down to 25 wt% and in nonlesional regions of the atopic dermatitis subjects down to 40 wt% compared to healthy controls. This "hydrocarbon chain length deficiency" regarding the barrier lipids in atopic skin was supported by metabolic labeling studies with [14C]-serine in cultured epidermis. The biosynthesis of free glucosylceramides and free ceramides was remarkably decreased in affected skin areas of the atopic subjects compared to healthy control subjects. Especially affected were the de novo syntheses of ceramide 4 (i.e., ceramide EOH, consisting of a very long chain N-acyl omega-hydroxy fatty acid esterified with linoleic acid and 6-hydroxysphingosine as sphingoid base) and ceramide 3 (ceramide NP, consisting of a nonhydroxy N-acyl fatty acid and phytosphingosine). In conclusion, this study revealed that the lesional epidermis in atopic dermatitis has considerable deficiencies within main barrier lipid components, which may contribute to the severely damaged permeability barrier.

Adolescent↗
PubMed1978

Variation of arylsulphatase A: comparative studies of arylsulphatase A with synthetic and natural substrates in three families with metachromatic leucodystrophy.

Arylsulphatase A activity was measured in leucocytes and cultured tibroblasts from individuals of three families with late infantile and adult metachromatic leucodystrophy, comparing enzyme assays with natural and two synthetic substrates including a simple and sensitive test employing 4-methylumbelliferly sulphate and AgNO3. Enzyme activities were compared with those obtained after isoelectric focusing. Arylsulphatase A values obtained for different heterozygotes were almost continuously scattered over the entire range from patient level to normal level. Nevertheless arylsulphatase A values of the heterozygotes were at least sligtly higher than the activity of diseases persons when measured with three different assays. The possibility is discussed of a crucial minimal level of residual arylsulphatase A activity necessary to avoid manifestation of the disease.

Adolescent↗
PubMed1977

Isoelectric focusing pattern of acid hydrolases in cultured fibroblasts, leucocytes and cell-free amniotic fluid.

The activities of 9 acid hydrolases were determined in cell-free amniotic fluid, leucocytes and cultured fibroblasts using fluorogenic substrates. The specific activities of beta-glucosidase, alpha-fucosidase, beta-hexosaminidase, and arylsulphatase A and B were found to be in the same range in cell-free amniotic fluid and in leucocyties. The isoenzyme pattern of these 5 hydrolases as well as that of acid phosphatase and alpha-mannosidase showed some similarities in all three specimens studied; the pattern of alpha- and beta-galactosidase obtained by isoelectric focusing was different in the 2 types of cells studied and in the cell-free amniotic fluid.

Acid Phosphatase↗
PubMed1989

[Immunotherapy following habitual abortion in paternal chromosome translocation].

In a 41-year-old VII-gravida, I-para, the husband's reciprocal translocation of the chromosomes 1 and 18 as well as a partial identity of the marital partner in the HLA-system may have been the underlying causes for five abortions. In the 7th pregnancy, a prenatal chromosome analysis was performed as well as an immunotherapy with paternal lymphocytes, when uterine bleeding occurred. After termination of bleeding, the pregnancy continued without any complication. Our case report demonstrates the importance of an extensive search for causes leading to recurrent abortions not only with regard to diagnosis but also with regard to therapy in pregnancy.

Abortion, Habitual↗
PubMed1984

Clinical course of GM2 gangliosidoses. A correlative attempt.

The clinical course of the early onset gangliosidoses can be explained on the basis of the developmental time course of different brain structures and functional systems. In particular, the maturation of the four basic motor control systems--spinal cord, brain stem and cerebellum, basal ganglia, cerebral cortex--determines the appearance of certain motor deficits. In late onset GM2 gangliosidoses, however, regional preference of the storage process has to be assumed in order to explain certain characteristic features of the disorder. An attempt is made to explain cellular dysfunction in GM2 storage disorders on the basis of developmental defects and/or destruction of the endoplasmatic reticulum and Golgi apparatus distortion of the neuronal geometry. Hyperirritability and epilepsy are possibly due to a dysequilibrium between excitatory and inhibitory postsynaptic influences caused by the distortion of the synaptic geometry on the nerve cell surface. Again, the clinical appearance of hyperirritability and the type of epilepsy are dependent upon the developmental age of the affected nervous system.

Axons↗
PubMed1984

Neurophysiological investigations in GM1 and GM2 gangliosidoses.

Neurophysiological studies (EEG, ERG, VEP and BAEP) have been carried out on a total of fifty-four patients (fourty-five GM2 and nine GM1 gangliosidosis) at various stages of the disease process. In infantile GM2 gangliosidosis, the EEG was midly abnormal from an early age but by the age of one year there was a rapid and progressive deterioration. EEG changes in late onset GM2 gangliosidosis were very variable and unrelated to age or enzyme defect. In both Type 1 and Type 2 GM1 gangliosidosis there was a progressive deterioration of the EEG. Paroxysmal features were not prominent in any of the gangliosidoses, despite the occurrence of seizures. The ERG remained normal in both GM2 and GM1 patients. In the infantile GM2 patients there was progressive loss of the VEP between nine and fifteen months of age but the timing of VEP changes were more variable in all the other groups. Evidence of brainstem dysfunction was found in one of the two TSD patients tested. The combined neurophysiological features appear to be characteristic for each group of gangliosidosis and differ from other neurometabolic disorders of childhood.

Arousal↗
PubMed1984

Morphology of the gangliosidoses.

GM1 and GM2 gangliosidoses are progressive neurodegenerative diseases which accumulate intralysosomal gangliosides--and to a lesser extent oligosaccharides--chiefly in the central and peripheral nervous system owing to deficiencies of beta-galactosidase and hexosaminidases A or/and B, respectively. This intralysosomal "storage" in neuronal pericarya and their processes, and subsequent loss of such nerve cells provide the background for clinical symptoms of the central nervous system and the retina, while involvement of the peripheral nervous system and the visceral organs largely remains free of clinical findings. The morphological involvement of the latter organs is widespread though varying, thus allowing morphological investigations of lymphocytes, skin, or rectum for morphological diagnosis and as a screening procedure.

Astrocytes↗
PubMed2005

Cell-specific deletion of glucosylceramide synthase in brain leads to severe neural defects after birth.

Sialic acid-containing glycosphingolipids, i.e., gangliosides, constitute a major component of neuronal cells and are thought to be essential for brain function. UDP-glucose:ceramide glucosyltransferase (Ugcg) catalyzes the initial step of glycosphingolipid (GSL) biosynthesis. To gain insight into the role of GSLs in brain development and function, a cell-specific disruption of Ugcg was performed as indicated by the absence of virtually all glucosylceramide-based GSLs. Shortly after birth, mice showed dysfunction of cerebellum and peripheral nerves, associated with structural defects. Axon branching of Purkinje cells was significantly reduced. In primary cultures of neurons, dendritic complexity was clearly diminished, and pruning occurred early. Myelin sheaths of peripheral nerves were broadened and focally severely disorganized. GSL deficiency also led to a down-regulation of gene expression sets involved in brain development and homeostasis. Mice died approximately 3 weeks after birth. These results imply that GSLs are essential for brain maturation.

Animals↗
PubMed2006

Identification of the protein receptor binding site of botulinum neurotoxins B and G proves the double-receptor concept.

Botulinum neurotoxins (BoNTs) cause muscle paralysis by selectively cleaving core components of the vesicular fusion machinery within motoneurons. Complex gangliosides initially bind into a pocket that is conserved among the seven BoNTs and tetanus neurotoxin. Productive neurotoxin uptake also requires protein receptors. The interaction site of the protein receptor within the neurotoxin is currently unknown. We report the identification and characterization of the protein receptor binding site of BoNT/B and BoNT/G. Their protein receptors, synaptotagmins I and II, bind to a pocket at the tip of their H(CC) (C-terminal domain of the C-terminal fragment of the heavy chain) that corresponds to the unique second carbohydrate binding site of tetanus neurotoxin, the sialic acid binding site. Substitution of amino acids in this region impaired binding to synaptotagmins and drastically decreased toxicity at mouse phrenic nerve preparations; CD-spectroscopic analyses evidenced that the secondary structure of the mutated neurotoxins was unaltered. Deactivation of the synaptotagmin binding site by single mutations led to virtually inactive BoNT/B and BoNT/G when assayed at phrenic nerve preparations of complex-ganglioside-deficient mice. Analogously, a BoNT B mutant with deactivated ganglioside and synaptotagmin binding sites lacked appreciable activity at wild-type mouse phrenic nerve preparations. Thus, these data exclude relevant contributions of any cell surface molecule other than one ganglioside and one protein receptor to the entry process of BoNTs, which substantiates the double-receptor concept. The molecular characterization of the synaptotagmin binding site provides the basis for designing a novel class of potent binding inhibitors.

Animals↗
PubMed2000

Histone deacetylase inhibitor selectively induces p21WAF1 expression and gene-associated histone acetylation.

Histone deacetylases (HDACs) catalyze the removal of acetyl groups on the amino-terminal lysine residues of core nucleosomal histones. This activity is associated generally with transcriptional repression. We have reported previously that inhibition of HDAC activity by hydroxamic acid-based hybrid polar compounds, such as suberoylanilide hydroxamic acid (SAHA), induces differentiation and/or apoptosis of transformed cells in vitro and inhibits tumor growth in vivo. SAHA is a potentially new therapeutic approach to cancer treatment and is in Phase I clinical trials. In several tumor cell lines examined, HDAC inhibitors alter the expression of less than 1% of expressed genes, including the cell cycle kinase inhibitor p21(WAF1). In T24 bladder carcinoma cells, SAHA induces up to a 9-fold increase in p21(WAF1) mRNA and protein, which is, at least in part, because of an increase in the rate of transcription of the gene. SAHA causes an accumulation of acetylated histones H3 and H4 in total cellular chromatin by 2 h, which is maintained through 24 h of culture. An increase in the accumulation of acetylated H3 and H4 was detected throughout the p21(WAF1) promoter and the structural gene after culture with SAHA. The level of histone acetylation did not change in chromatin associated with the actin and p27 genes, and their mRNA expression was not altered during culture of T24 cells with SAHA. Thus, the present findings indicate that the induction of p21(WAF1) by SAHA is regulated, at least in part, by the degree of acetylation of the gene-associated histones and that this induced increase in acetylation is gene selective.

Anticarcinogenic Agents↗
PubMed1978

Membrane-bound neuraminidase from calf brain: regulation of oligosialoganglioside degradation by membrane fluidity and membrane components.

The degradation of lipophilic ganglioside GD1a and hydrophilic sialyllactitol by membrane-bound neuraminidase (EC 3.2.1.18) from calf brain has been studied at substrate concentrations of 0.1 mM. Ganglioside GD1a taken up by cell membranes is hydrolyzed faster membrane-bound neuraminidase than are water-soluble substrates of the enzyme, sialyllactitol and des-GD1a. Availability and enzymic breakdown of the disialoganglioside are enhanced by general anesthetics such as N2O or halothane whereas the degradation of the hydrophilic substrate silayllactitol is not affected or even is decreased by these agents. General anesthetics lower the microviscosity of membranes as indicated by studies of fluorescence depolarization with the indicator 1,6-diphenylhexatriene. Increased fluidity can result in higher lateral diffusion of ganglioside GD1a, thus increasing its chances of presentation to, and interaction with, membrane-bound neuraminidase. Lipophilic derivatives of the disialoganglioside, gangliosides GM1 and GM2 and gangliotriaosylceramide GA2, are strong inhibitors of the ganglioside degradation whereas water-soluble derivatives des-GM1, des-GM2, N-acetylneuraminic acid, and sialyllactose are not. A model is presented that suggests that the activity of membrane-bound neuraminidase on gangliosides of brain membranes is regulated by the viscosity of these membranes and their monosialoganglioside content.

Anesthesia, General↗
PubMed1978

AB variant of infantile GM2 gangliosidosis: deficiency of a factor necessary for stimulation of hexosaminidase A-catalyzed degradation of ganglioside GM2 and glycolipid GA2.

Human kidney extracts heated to 60 degrees and devoid of hexosaminidase activity (2-acetamido-2-deoxy-beta-D-glucoside acetamidodeoxyglucohydrolase EC 3.2.1.30) stimulate more than 20-fold the hexosaminidase A-catalyzed degradation of ganglioside GM2 and of glycolipid GA2, the neuronal storage compounds of GM2 gangliosidosis. The stimulating factor of this extract, which is labile at temperatures above 60 degrees, is also present in kidney extracts from patients with infantile GM2 gangliosidosis having a deficiency of hexosaminidase A (Tay-Sachs disease, variant B) and a deficiency of hexosaminidases A and B (variant 0). Evidence is presented that this factor is defective in the AB-variant of infantile GM2 gangliosidosis which is characterized by an accumulation of glycolipids GM2 and GA2 despite the fact that the degrading enzymes, hexosaminidases A and B, retain normal activity levels. Thus, variant AB is an example of a fatal lipid storage disease that is caused not by a defect of a degrading enzyme but rather by a defective factor necessary for the interaction of lipid substrates and the water-soluble hydrolase.

Enzyme Activation↗
PubMed1983

Tunicamycin inhibits ganglioside biosynthesis in rat liver Golgi apparatus by blocking sugar nucleotide transport across the membrane vesicles.

The synthesis of ganglioside GM1 in intact rat liver Golgi-derived vesicles is stimulated by phosphatidylglycerol as much (about 20-fold) as by Triton X-100. The antibiotic tunicamycin inhibits strongly the synthesis, in the presence as well as in the absence of the phospholipid, but has no effect when Golgi membranes are solubilized with detergent. In Pronase-treated Golgi vesicles, which retain full enzyme activity, both phospholipid dependence and tunicamycin inhibition of the synthesis disappear completely. When freshly prepared Golgi vesicles are incubated with 125 microM UDP-[3H]Gal for 10 min at 30 degrees C, the nucleotide sugar is found to be transported into the vesicles at an approximate rate of about 85 pmol/mg of protein per min, 92% of which remains firmly bound to the membrane. Tunicamycin inhibits this transport in a concentration-dependent manner. These results indicate the existence of carrier proteins in rat liver Golgi vesicles, which mediate the transport of the sugar nucleotide UDP-Gal, and that the carriers face the cytoplasmic side of the vesicles. The results also show that, although the mechanism of phosphatidylglycerol-induced stimulation of the synthetic activity remains unclear, tunicamycin inhibits ganglioside biosynthesis by blocking the transport of the nucleotide sugar and not by inhibiting the transferase directly.

Animals↗
PubMed1988

Both GA2, GM2, and GD2 synthases and GM1b, GD1a, and GT1b synthases are single enzymes in Golgi vesicles from rat liver.

Competition experiments using lactosylceramide, ganglioside GM3 and ganglioside GD3 as substrates, as well as mutual inhibitors for ganglioside N-acetylgalactosaminyltransferase, in Golgi vesicles derived from rat liver suggested that N-acetylgalactosamine transfer to these three respective compounds, leading to gangliosides GA2, GM2, and GD2, respectively, is catalyzed by one enzyme. Analogous studies with gangliosides GA1, GM1, and GD1b as glycolipid acceptors in sialyltransferase assays indicated GM1b, GD1a, and GT1b synthases to be identical. These results are incorporated into a model for ganglioside biosynthesis and its regulation.

Algorithms↗
PubMed1988

Gene encoding the human beta-hexosaminidase beta chain: extensive homology of intron placement in the alpha- and beta-chain genes.

Lysosomal beta-hexosaminidase (EC 3.2.1.52) is composed of two structurally similar chains, alpha and beta, that are the products of different genes. Mutations in either gene causing beta-hexosaminidase deficiency result in the lysosomal storage disease GM2-gangliosidosis. To enable the investigation of the molecular lesions in this disorder and to study the evolutionary relationship between the alpha and beta chains, the beta-chain gene was isolated, and its organization was characterized. The beta-chain coding region is divided into 14 exons distributed over approximately 40 kilobases of DNA. Comparison with the alpha-chain gene revealed that 12 of the 13 introns interrupt the coding regions at homologous positions. This extensive sharing of intron placement demonstrates that the alpha and beta chains evolved by way of the duplication of a common ancestor.

Amino Acid Sequence↗
PubMed1997

Quantitative analysis of biological membrane lipids at the low picomole level by nano-electrospray ionization tandem mass spectrometry.

Nano-electrospray tandem mass spectrometry allows qualitative and quantitative analysis of complex membrane lipid mixtures at the subpicomole level. We have exploited this technique to selectively detect individual classes of phospholipids from unprocessed total cellular lipid extracts by either precursor ion or neutral loss scanning. This way phosphatidylcholine, sphingomyelin, phosphatidylinositol and -phosphates, phosphatidylethanolamine, phosphatidylserine, phosphatidylglycerol, phosphatidic acid, and their plasmalogen analogues can be detected. The optimized ionization and fragmentation conditions described together with the principle of internal standardization by nonnatural analogues allow the rapid and quantitative determination of membrane lipid compositions down to sample amounts of 1000 cells.

Animals↗
PubMed1998

Mice with type 2 and 3 Gaucher disease point mutations generated by a single insertion mutagenesis procedure.

Gaucher disease is caused by mutations in the gene encoding the lysosomal enzyme glucocerebrosidase (GC). Three clinical types of Gaucher disease have been defined according to the presence (type 2 and 3) or absence (type 1) of central nervous system disease and severity of clinical manifestations. The clinical course of the disease correlates with the mutation carried by the GC gene. To produce mice with point mutations that correspond to the clinical types of Gaucher disease, we have devised a highly efficient one-step mutagenesis method-the single insertion mutagenesis procedure (SIMP)-to introduce human disease mutations into the mouse GC gene. By using SIMP, mice were generated carrying either the very severe RecNciI mutation that can cause type 2 disease or the less severe L444P mutation associated with type 3 disease. Mice homozygous for the RecNciI mutation had little GC enzyme activity and accumulated glucosylceramide in brain and liver. In contrast, the mice homozygous for the L444P mutation had higher levels of GC activity and no detectable accumulation of glucosylceramide in brain and liver. Surprisingly, both point mutation mice died within 48 hr of birth, apparently of a compromised epidermal permeability barrier caused by defective glucosylceramide metabolism in the epidermis.

Amino Acid Sequence↗