No Fabry Disease in Patients Presenting with Isolated Small Fiber Neuropathy

Objective

Screening for Fabry disease in patients with small fiber neuropathy has been suggested, especially since Fabry disease is potentially treatable. However, the diagnostic yield of testing for Fabry disease in isolated small fiber neuropathy patients has never been systematically investigated. Our aim is to determine the presence of Fabry disease in patients with small fiber neuropathy.

Methods

Patients referred to our institute, who met the criteria for isolated small fiber neuropathy were tested for Fabry disease by measurement of alpha-Galactosidase A activity in blood, lysosomal globotriaosylsphingosine in urine and analysis on possible GLA gene mutations.

Results

725 patients diagnosed with small fiber neuropathy were screened for Fabry disease. No skin abnormalities were seen except for redness of the hands or feet in 30.9% of the patients. Alfa-Galactosidase A activity was tested in all 725 patients and showed diminished activity in eight patients. Lysosomal globotriaosylsphingosine was examined in 509 patients and was normal in all tested individuals. Screening of GLA for mutations was performed for 440 patients, including those with diminished α-Galactosidase A activity. Thirteen patients showed a GLA gene variant. One likely pathogenic variant was found in a female patient. The diagnosis Fabry disease could not be confirmed over time in this patient. Eventually none of the patients were diagnosed with Fabry disease.

Conclusions

In patients with isolated small fiber neuropathy, and no other signs compatible with Fabry disease, the diagnostic yield of testing for Fabry disease is extremely low. Testing for Fabry disease should be considered only in cases with additional characteristics, such as childhood onset, cardiovascular disease, renal failure, or typical skin lesions.     

Requirement for galectin-3 in apical protein sorting

The central aspect of epithelial cells is their polarized structure, characterized by two distinct domains of the plasma membrane, the apical and the basolateral membrane. Apical protein sorting requires various signals and different intracellular routes to the cell surface. The first apical targeting motif identified is the membrane anchoring of a polypeptide by glycosyl-phosphatidyl-inositol (GPI). A second group of apical signals involves N- and O-glycans, which are exposed to the luminal side of the sorting organelle. Sucrase-isomaltase (SI) and lactase-phlorizin hydrolase (LPH), which use separate transport platforms for trafficking, are two model proteins for the study of apical protein sorting. In contrast to LPH, SI associates with sphingolipid/cholesterol-enriched membrane microdomains or "lipid rafts". After exit form the trans-Golgi network (TGN), the two proteins travel in distinct vesicle populations, SAVs (SI-associated vesicles) and LAVs (LPH-associated vesicles) . Here, we report the identification of the lectin galectin-3 delivering non-raft-dependent glycoproteins in the lumen of LAVs in a carbohydrate-dependent manner. Depletion of galectin-3 from MDCK cells results in missorting of non-raft-dependent apical membrane proteins to the basolateral cell pole. This suggests a direct role of galectin-3 in apical sorting as a sorting receptor.     

Electron transfer ability from NADH to menaquinone and from NADPH to oxygen of type II NADH dehydrogenase of Corynebacterium glutamicum

Type II NADH dehydrogenase of Corynebacterium glutamicum (NDH-2) was purified from an ndh overexpressing strain. Purification conferred 6-fold higher specific activity of NADH:ubiquinone-1 oxidoreductase with a 3.5-fold higher recovery than that previously reported (K. Matsushita et al., 2000). UV-visible and fluorescence analyses of the purified enzyme showed that NDH-2 of C. glutamicum contained non-covalently bound FAD but not covalently bound FMN. This enzyme had an ability to catalyze electron transfer from NADH and NADPH to oxygen as well as various artificial quinone analogs at neutral and acidic pHs respectively. The reduction of native quinone of C. glutamicum, menaquinone-2, with this enzyme was observed only with NADH, whereas electron transfer to oxygen was observed more intensively with NADPH. This study provides evidence that C. glutamicum NDH-2 is a source of the reactive oxygen species, superoxide and hydrogen peroxide, concomitant with NADH and NADPH oxidation, but especially with NADPH oxidation. Together with this unique character of NADPH oxidation, phylogenetic analysis of NDH-2 from various organisms suggests that NDH-2 of C. glutamicum is more closely related to yeast or fungal enzymes than to other prokaryotic enzymes.     

LmxMPK4, a mitogen-activated protein (MAP) kinase homologue essential for promastigotes and amastigotes of <Emphasis Type="Italic">Leishmania mexicana</Emphasis>

Background  

Leishmania parasites undergo profound morphological and biochemical changes while passing through their life cycle. Protein kinases have been shown to be involved in the differentiation from the extracellular flagellated promastigotes to the intracellular "non-flagellated" amastigotes and vice versa. Moreover, these enzymes are likely involved in the regulation of the proliferation of the different life stages.     

Protein expressed by the ho2 gene of the cyanobacterium Synechocystis sp. PCC 6803 is a true heme oxygenase. Properties of the heme and enzyme complex

Two isoforms of a heme oxygenase gene, ho1 and ho2, with 51% identity in amino acid sequence have been identified in the cyanobacterium Synechocystis sp. PCC 6803. Isoform-1, Syn HO-1, has been characterized, while isoform-2, Syn HO-2, has not. In this study, a full-length ho2 gene was cloned using synthetic DNA and Syn HO-2 was demonstrated to be highly expressed in Escherichia coli as a soluble, catalytically active protein. Like Syn HO-1, the purified Syn HO-2 bound hemin stoichiometrically to form a heme-enzyme complex and degraded heme to biliverdin IXalpha, CO and iron in the presence of reducing systems such as NADPH/ferredoxin reductase/ferredoxin and sodium ascorbate. The activity of Syn HO-2 was found to be comparable to that of Syn HO-1 by measuring the amount of bilirubin formed. In the reaction with hydrogen peroxide, Syn HO-2 converted heme to verdoheme. This shows that during the conversion of hemin to alpha-meso-hydroxyhemin, hydroperoxo species is the activated oxygen species as in other heme oxygenase reactions. The absorption spectrum of the hemin-Syn HO-2 complex at neutral pH showed a Soret band at 412 nm and two peaks at 540 nm and 575 nm, features observed in the hemin-Syn HO-1 complex at alkaline pH, suggesting that the major species of iron(III) heme iron at neutral pH is a hexa-coordinate low spin species. Electron paramagnetic resonance (EPR) revealed that the iron(III) complex was in dynamic equilibrium between low spin and high spin states, which might be caused by the hydrogen bonding interaction between the distal water ligand and distal helix components. These observations suggest that the structure of the heme pocket of the Syn HO-2 is different from that of Syn HO-1.     

Hydrogen peroxide and expression of hipI-superoxide dismutase are associated with the development of secondary cell walls in Zinnia elegans

A special form of a CuZn-superoxide dismutase with a high isoelectric point (hipI-SOD; EC 1.15.1.1) and hydrogen peroxide (H2O2) production were studied during the secondary cell wall formation of the inducible tracheary element cell-culture system of Zinnia elegans L. Confocal microscopy after labelling with 2',7'-dichlorofluorescin diacetate showed H2O2 to be located largely in the secondary cell walls in developing tracheary elements. Fluorescence-activated cell sorting analysis showed there were lower levels of H2O2 in the population containing tracheary elements when H2O2 scavengers such as ascorbate, catalase, and reduced glutathione were applied to the cell culture. Inhibitors of NADPH oxidase and SOD also reduced the amount of H2O2 in the tracheary elements. Furthermore, addition of these compounds to cell cultures at the time of tracheary element initiation reduced the amount of lignin and the development of the secondary cell walls. Analysis of UV excitation under a confocal laser scanning microscope confirmed these results. The expression of hipI-SOD increased as the number of tracheary elements in the cell culture increased and developed. Additionally, immunolocalization of a hipI-SOD isoform during the tracheary element differentiation showed a developmental build-up of the protein in the Golgi apparatus and the secondary cell wall. These findings suggest a novel hipI-SOD could be involved in the regulation of H2O2 required for the development of the secondary cell walls of tracheary elements.     

Immunity and beta-endorphin concentrations in hypothalamus and plasma in rats with steroid-induced polycystic ovaries: effect of low-frequency electroacupuncture

The human endocrinological disorder polycystic ovary syndrome (PCOS) is a common cause of reproductive failure. Even though the cause of PCOS is unknown, hormone and immune disturbances as well as hyperactivity in the sympathetic nervous system are likely to be involved in the pathogenesis of the disease. The present study was undertaken to elucidate if rats with estradiol valerate (EV)-induced polycystic ovaries (PCO) have altered beta-endorphin concentrations in the hypothalamus and in plasma and if they have alterations in circulating immune cell populations and the activity. Repeated low-frequency (2 Hz) electroacupuncture (EA) treatments are known to modulate the release of beta-endorphin, immune responses, and the activity in the autonomic nervous system. We therefore also investigated the effect of EA treatments on the beta-endorphin and the immune systems. Low-frequency EA was given 12 times, 25 min each, over 30 days starting 2-3 days after i.m. injection of EV. The beta-endorphin concentrations in the hypothalamus and in plasma as well as the frequencies of CD4+ T cells and CD8+ T cells were significantly lower in EV-injected control rats as compared to oil-injected control rats. Repeated EA treatments in EV-injected rats significantly increased beta-endorphin concentrations in the hypothalamus. In conclusion, these findings show that both the beta-endorphinergic and the immune system are significantly impaired in rats with steroid-induced PCO and that repeated EA treatments can restore some of these disturbances.     

When sparks get old

Sparks are transient local elevations of Ca ion concentration observed in different types of muscle cells. Such local Ca2+ signals can be provoked in skeletal muscle cells by altering the osmotic pressure of the extracellular solution. In this issue, Weisleder et al. (see p. 639) demonstrate that the Ca2+ response to osmotic stress is substantially altered in aged muscle. The study presents evidence for a link between this finding and a reduced expression of mitsugumin 29 (MG29), a small membrane protein of the sarcoplasmic reticulum (SR).     

Lithologic controls on biogenic silica cycling in South African savanna ecosystems

The efficacy of higher plants at mining Si from primary and secondary minerals in terrestrial ecosystems is now recognized as an important weathering mechanism. Grassland ecosystems are a particularly large reservoir of biogenic silica and are thus likely to be a key regulator of Si mobilization. Herein, we examine the effects of parent material (basaltic and granitic rocks) on the range and variability of biogenic silica pools in grass-dominated ecosystems along two precipitation gradients of Kruger National Park, South Africa. Four soil pedons and adjacent dominant plant species were characterized for biogenic silica content. Our results indicate that although soils derived from basalt had less total Si and dissolved Si than soils derived from granite, a greater proportion of the total Si was made up of biogenically derived silica. In general, plants and soils overlying basaltic versus granitic parent material stored greater quantities of biogenic silica and had longer turnover times of the biogenic silica pool in soils. Additionally, the relative abundance of biogenic silica was greater at the drier sites along the precipitation gradient regardless of parent material. These results suggest that the biogeochemical cycling of Si is strongly influenced by parent material and the hydrologic controls parent material imparts on soils. While soils derived from both basalt and granite are strongly regulated by biologic uptake, the former is a “tighter” system with less loss of Si than the latter which, although more dependent on biogenic silica dissolution, has greater losses of total Si. Lithologic discontinuities span beyond grasslands and are predicted to also influence biogenic silica cycling in other ecosystems.