Effect of the 50 bp deletion polymorphism in the SOD1 promoter on SOD1 mRNA levels in Italian ALS patients.

The genetic association between homozygosity for a 50 bp deletion polymorphism in the SOD1 promoter, 1684 bp upstream of the ATG, and an increased age of symptom onset was observed in various populations of ALS patients. Moreover, it has been demonstrated that this deletion reduces SOD1 expression in vitro. The objective of the present study was to test whether the observed association is replicated in patients from an Italian population and to check whether the deletion correlates with reduced SOD1 mRNA expression in vivo. Genomic DNA from 235 Italian SALS cases and 245 age- and sex-matched donors from the same ethnic background was screened for the 50 bp SOD1 promoter deletion by real time PCR assays. No differences were observed between ALS patients and controls for the frequency of both the alleles (D=deleted, N=non-deleted; p=0.95) and genotypes (p=0.90). Furthermore, stratification of the ALS samples showed that this variation was not associated with increased age of onset in ND and DD patients in comparison to NN patients (p=0.48). Finally, we performed real-time RT-PCR to quantify SOD1 mRNA levels in 48 patients and we did not find a relevant difference among the three sub-groups of genotypes (p=0.30). Our data suggest that the studied polymorphism does not modulate SOD1 mRNA level and disease phenotype in an Italian population.

Peripheral expression of key regulatory kinases in Alzheimer's disease and Parkinson's disease.

Alteration of key regulatory kinases may cause aberrant protein phosphorylation and aggregation in Alzheimer's disease (AD) and Parkinson's disease (PD). In this study, we investigated expression and phosphorylation status of glycogen synthase kinase 3 (GSK-3), protein kinase B (Akt) and tau protein in peripheral blood lymphocytes of 20 AD, 25 PD patients and 20 healthy controls. GSK-3 was increased in AD and PD patients. In these latter, GSK-3 levels were positively correlated with daily L-Dopa intake. Phosphorylated Akt expression was augmented in both groups; total Akt levels were increased only in AD patients and were positively correlated with disease duration and severity. Total and phosphorylated tau were increased only in AD, with phospho-tau levels being positively correlated with levels of total tau, Akt, and disease duration. No correlations between protein levels and clinical variables were found in PD patients. Investigation of peripheral changes in the expression of specific kinases may, therefore, lead to the development of innovative biomarkers of neurodegeneration, particularly for AD.

Effect of nitric oxide on lymphocytes from sporadic amyotrophic lateral sclerosis patients: toxic or protective role?

Markers of oxidative and nitrosative stress have been found in spinal cord, cortex, cerebrospinal fluid and plasma of patients affected by amyotrophic lateral sclerosis (ALS), a fatal disorder characterised by progressive motor neuron degeneration. In this study, we investigated the effect of the NO-releasing agent, diethylamine NONOate (NONO), on lymphocytes from patients affected by the sporadic form of ALS (SALS) and controls by flow cytometry. In the same experimental conditions we investigated the expression of the antioxidant proteins, Bcl-2 and SOD1. Incubation with NONO induced cell damage in control lymphocytes but did not further damage the already affected untreated SALS lymphocytes. The incubation with NONO induced a time-dependent decrease of Bcl-2 and SOD1 in control lymphocytes. Surprisingly, in SALS lymphocytes the NONO treatment increased the expression of these proteins, which in basal conditions was depressed compared to control lymphocytes.

Water movement across rat bile duct units is transcellular and channel-mediated.

In recent studies using freshly isolated rat cholangiocytes, we established that water crosses the cholangiocyte membrane by a channel-mediated mechanism involving aquaporins, a family of water-channel proteins. Our goal was to address the importance of channel-mediated water transport in ductal bile formation by employing a physiologic experimental model, the enclosed, polarized rat intrahepatic bile duct unit (IBDU). Expansion and reduction of luminal areas as a reflection of water movement into and out of IBDUs prepared from livers of normal rats were measured by quantitative computer-assisted image analysis. When enclosed IBDUs were exposed to inward or outward osmotic gradients, their luminal area rapidly increased (approximately 25%) or decreased (approximately 20%) reflecting net water secretion or absorption, respectively. These effects were specifically inhibited by 2 water channel blockers, DMSO and HgCl2. In both instances, beta-mercaptoethanol reversed the inhibitory effects. In the absence of an osmotic gradient, choleretic agents (secretin and forskolin) and a cholestatic hormone (somatostatin) induced a significant increase or decrease of IBDU luminal area by 21% and 22%, respectively. These effects were also inhibited by DMSO and reversed by beta-mercaptoethanol. Under our experimental conditions, DMSO did not interfere with either forskolin-induced cAMP synthesis or the generation of osmotic driving forces via the apical chloride-bicarbonate exchanger. Protamine, an inhibitor of the paracellular pathway, had no effect on hypotonic or forskolin-induced water secretion in IBDUs. These results in a physiologically relevant model of ductal bile formation provide additional support for the concept that osmotically driven and agonist-stimulated water movement into (secretion) and out of (absorption) the biliary ductal lumen is transcellular and water channel-mediated.

Transport of thiamin in rat renal brush border membrane vesicles.

BACKGROUND: Unlike intestinal absorption, renal transport of thiamin has received little attention. This study was designed to investigate the reabsorptive steps of thiamin transport in brush border membrane vesicles (BBMVs) from rat kidney proximal tubules using tritiated thiamin with a high specific activity. METHODS: BBMVs prepared from the cortex kidney of rats were suspended in different media, controlling the composition of the intravesicular fluid by prolonged equilibration at 4 degrees C in preincubation buffers of desired composition. Then they were held on ice until used, when they were warmed at 25 degrees C for the uptake experiments. The amount of radioactivity taken up by the vesicles was measured radiometrically after separation with a rapid-filtration procedure. RESULTS: The time course profile of thiamin uptake was Na+ independent; 53% of thiamin taken up was membrane bound. The concentration curve had a biphasic course that was nonlinear (saturable) at physiological concentrations (<1.25 micromol/L) and linear at higher ones. Thiamin uptake was stimulated several-fold by an outwardly directed H+ gradient (pHin 6:pHout 7.5), which caused a transient accumulation of thiamin inside BBMVs against a concentration gradient. The enhanced thiamin uptake was only due to the H+ gradient, which made thiamin binding virtually negligible compared with translocation, and maintained the biphasic course of the concentration curve. The saturable component, however, had kinetic constants 12-fold higher than those in the absence of gradient. Moreover, the saturable component was inhibited by nonlabeled thiamin and its structural analogues, by inhibitors of intestinal thiamin/H+, renal guanidine/H+, and Na+/H+ antiporters, while it remained unmodified by some typical organic cations transported in renal BBMVs. CONCLUSION: The results provide strong evidence for the presence in renal BBMVs of a thiamin/H+ antiport having a 1:1 stoichiometric ratio.

Significance of ammonia in the genesis of gastric epithelial lesions induced by Helicobacter pylori: an in vitro study with different bacterial strains and urea concentrations.

Two Helicobacter pylori products cause cell damage both in vivo and in vitro: ammonia, from bacterial urease activity, and a vacuolating toxin named VacA. In this in vitro study, the vacuolating effect of H. pylori broth culture filtrate from a VacA-positive/urease-positive strain is compared with that of a VacA-negative/urease-positive strain and a VacA-negative/urease-negative strain. The effect of VacA and ammonia was evaluated with and without addition of 10 mM urea, a physiological concentration for the human stomach, and with and without addition of 0.5 mg/ml acetohydroxamic and (AHA), an urease inhibitor. Our data show that: (1) both urease-positive H. pylori strains caused cell vacuolation in the absence of urea, the VacA-positive strain being approximatively twice as potent as the VacA-negative strain; (2) addition of urea to the culture medium caused an approximatively 3-fold increase in the vacuolating activity of both urease-positive strains; (3) a VacA-negative/urease-negative strain did not exert any vacuolating effect, either in the presence or in the absence of urea; (4) the ratio between cell vacuolation induced by VacA-positive and VacA-negative strains was enhanced by the presence of AHA: ratio was about 2 in the absence of AHA and about 6 in the presence of AHA, either with or without urea added. The increment of vacuolation is likely due to an interaction between AHA and VacA. In conclusion, a VacA-negative/urease-positive strain becomes highly cytotoxic when physiological levels of urea are present in the incubation medium. This finding suggests that all urease-positive H. pylori strains, both with and without VacA expression, should be considered as potentially cytotoxic for the human gastric mucosa, although VacA enhances the severity of cell damage.

Na+,K(+)-ATPase of gastric cells. A target of Helicobacter pylori cytotoxic activity.

The present study shows a direct impairing action of a cytotoxin-producing Helicobacter pylori strain on the Na+,K(+)-ATPase (evaluated as K(+)-dependent phosphatase activity) of human gastric epithelial cells in culture. The toxin itself is likely involved in this action which may also account for the cell edema found in vivo in Helicobacter pylori-colonized stomach.

Dynamics of nonprotein and protein sulfhydryl compounds in rat gastric mucosa: possible implication for cytoprotection and ulcerogenesis.

The hypothesis that nonprotein and protein sulfhydryls in gastric mucosa may play some role in the defensive and offensive processes of gastric epithelium was tested in this study in the intact rat gastric mucosa. Both sulfhydryl compounds presented statistically significant changes during the 24-hour day. The content of nonprotein sulfhydryls was less during the dark span than during the light span, while the circadian acrophase of protein sulfhydryls occurred during dark span. These results may offer a new interpretation of the greater vulnerability to ulcerogenic agents of the gastric mucosa of rats during their usual activity span.