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Biomedical subjects

C Valle

Publications and source records attributed to C Valle.

18 recordsLinked to original sources
PubMed2001

Crack characterization using guided circumferential waves.

This paper examines the propagation of guided circumferential waves in a hollow isotropic cylinder that contains a crack, with the goal of using these guided waves to both locate and size the crack. The crack is sized using a modified Auld's formula, which relates the crack's length to a reflected energy coefficient. The crack is then located by operating on the backscattered signal with a time-frequency digital signal processing (DSP) technique, and then comparing these results to those obtained if the cylinder is perfect. The guided circumferential waves are generated with a commercial finite element method (FEM) code. One objective of this work is to demonstrate the effectiveness of using sophisticated DSP techniques to describe the effect of scattering on dispersive waves, showing it is possible to characterize cracks systematically and accurately by quantifying this scattering effect. The results show that the need for high frequency signals to detect small cracks is significantly decreased by using these techniques.

Journal Article↗
PubMed2000

Drugs of abuse modulate the phosphorylation of ARPP-21, a cyclic AMP-regulated phosphoprotein enriched in the basal ganglia.

ARPP-21 is a cyclic AMP-regulated phosphoprotein of M(r) 21 kDa that is enriched in the cell bodies and terminals of medium-sized spiny neurons in the basal ganglia. Using a new phosphorylation state-specific antibody selective for the detection of ARPP-21 phosphorylated on Ser(55), we have demonstrated that activation of dopamine D1 receptors increased the level of ARPP-21 phosphorylation in mouse striatal slices. Conversely, activation of D2 receptors caused a large decrease in ARPP-21 phosphorylation. Treatment of mice with either methamphetamine or cocaine resulted in increased ARPP-21 phosphorylation in vivo. Studies using specific inhibitors of protein phosphatases and experiments in mice bearing a targeted deletion of the gene for DARPP-32, a dopamine-activated inhibitor of protein phosphatase-1, indicated that protein phosphatase-2A is primarily responsible for dephosphorylation of ARPP-21 in mouse striatum. These results demonstrate that phosphorylation and dephosphorylation of ARPP-21 are tightly regulated in the striatum. We speculate that ARPP-21 might mediate some of the physiologic effects of dopamine and certain drugs of abuse in the basal ganglia.

Animals↗
PubMed2000

Molecular cloning of Schistosoma mansoni calcineurin subunits and immunolocalization to the excretory system.

In order to explain the schistosomicidal effect of cyclosporin A, the hypothesis was advanced that the drug, complexed with cyclophilin, inhibits the phosphatase activity of parasite calcineurin (CN), with mechanisms similar to those operating in its immunosuppressive action. As a preparatory step to the testing of this hypothesis, we report the molecular cloning of both CN subunits in Schistosoma mansoni. The catalytic (A) subunit has a predicted sequence of 607 amino acids and shows substantial similarity to other cloned CNs, except for the carboxy-terminal end that is highly divergent. The regulatory (B) subunit consists of 169 amino acids that are 86% identical to those of the human counterpart and, from its anomalous electrophoretic mobility, it appears to be myristoylated. The results of Southern blotting experiments are compatible with the existence of multiple genes for CNA and a single gene for CNB. Western blots showed that both subunits are present at all stages of the parasite life cycle and can be detected both in the soluble and in the membrane fraction. Immunofluorescence confocal microscopy revealed a striking concentration of the anti-CNA reactivity in 6-8 discrete spots in the schistosomula and in distinct spots along the body of the adult parasite, corresponding to the expected localization of flame cells. Both patterns were confirmed by a perfect co-localization of the anti-CNA signal with that of a previously characterized anti-flame cell monoclonal antibody. The preferential confinement of schistosome CN to the protonephridial system suggests that the enzyme in the parasite may fulfil similar functions to those performed in mammalian kidneys.

Amino Acid Sequence↗
PubMed1999

Stage-specific expression of a Schistosoma mansoni polypeptide similar to the vertebrate regulatory protein stathmin.

The ubiquitous vertebrate protein stathmin is expressed and phosphorylated in response to a variety of external and internal signals. Stathmin, in turn, controls cell growth and differentiation through its capacity to regulate microtubule assembly dynamics. This is the first report on the molecular cloning and characterization of a stathmin-like protein (SmSLP) in an invertebrate, the human blood fluke Schistosoma mansoni. SmSLP is first synthesized at high levels in the intermediate molluscan host and completely disappears 48 h after penetration into the mammalian host. The protein is preferentially iodinated in intact immature parasites using the Bolton-Hunter reagent, can be quantitatively extracted in high salt buffers, and remains soluble after boiling. Native SmSLP was partially sequenced, and its complete structure was derived from the cloning and sequencing of its cDNA. The sequence is up to 26% identical to vertebrate stathmin sequences and contains two potential phosphorylation sites. Native SmSLP is indeed phosphorylated because phosphatase digestion shifts its mobility in electrofocusing gels. SmSLP associates with tubulin, as suggested by immune co-precipitation results. In vitro experiments demonstrated that SmSLP inhibits tubulin assembly and causes the depolymerization of preassembled microtubules, thus probably fulfilling regulatory roles in critical steps of schistosome development.

Amino Acid Sequence↗
PubMed1999

Prevalence and impact of symptoms suggestive of gastroesophageal reflux disease.

Few studies have focused on the impact of gastroesophageal reflux disease on general health and on work absenteeism. Our aim was to evaluate the prevalence and severity of symptoms suggestive of gastroesophageal reflux disease in two samples of Italian employees. We interviewed 424 subjects of S. Matteo Hospital staff and 344 subjects of the Military Factory of Pavia regarding the frequency and severity of heartburn and acid regurgitation during the last 12 months. Subjects were specifically asked whether symptoms interfered with the quality of work activities or determined work absenteeism. In all, 91% of eligible subjects responded. The prevalence rate per 100 of any heartburn or regurgitation experienced at least monthly was 21. This value increased to 45% taking into consideration symptoms experienced occasionally. Mild or moderate symptoms were more frequent than severe symptoms (P < 0.001). Only 2.6% of subjects answered that symptoms have a negative influence on the quality of their work. No work absenteeism was recorded. The study confirms that typical gastroesophageal reflux symptoms are common conditions, but mainly of mild or moderate degree.

Adult↗
PubMed1998

Prevention of rotavirus diarrhoea in foals by parenteral vaccination of the mares: field trial.

Many countries have reported rotavirus diarrhoea in foals. In Argentina it causes important economic losses to the horse industry. In this work we present the results obtained using an experimental vaccine in a farm with enzootic infection of rotavirus. A hundred mares were vaccinated 60 and 30 days before foaling with inactivated rotavirus SA11 (G3P2), H2 (G3P12), Lincoln (G6P1), with aluminum hydroxide as adjuvant; 65 mares were included in the unvaccinated, control group. To evaluate the vaccine, morbidity, duration of the diarrhoea and rotavirus shedding were recorded. Antibody levels were established in serum, colostrum and milk of the vaccinated mares, and also in serum from the foals. In foals from vaccinated mares the morbidity was 30%, clinical signs were observed during 1.8 days, and rotavirus shedding was not detected. In the control group the morbidity reached 80%, the clinical signs lasted 7.3 days and rotavirus shedding was detected in 80% of the diarrhoeic foals. At foaling the serum antibody levels were 15 times higher with a mean neutralizing titre (NT) of 3.5 logs than before vaccination (2.4 logs), in colostrum 5.00 logs, and in milk at 90 days post partum 1.7 logs. In foals from vaccinated mares the level of neutralizing antibodies was 3.8 logs at 48 days of age, going down to 2.2 logs at 90 days of age. Immunization of the pregnant mare would be a good method for preventing diarrhoea in foals.

Animals↗
PubMed1995

Characterization of a Schistosoma mansoni cDNA encoding a B-like cyclophilin and its expression in Escherichia coli.

A cDNA encoding a Schistosoma mansoni cyclophilin (SmCyP) has been cloned by polymerase chain reaction amplification using degenerate oligonucleotides based on known conserved cyclophilin (CyP) sequences and by screening an expression cDNA library. The cDNA sequence encodes a 21.5-kDa protein, which shares 59% sequence identity with human CyP B. The SmCyP protein was expressed in Escherichia coli with a hexahistidine affinity tag at its amino terminus and antibodies to the purified (His6)-SmCyP fusion protein were raised in a rabbit. Fractionation of parasite material followed by immunoblot analysis revealed that schistosome CyP is a soluble protein. The N-terminus of the predicted protein contains a hydrophobic region, suggestive of a signal sequence. Accordingly, a recombinant SmCyP protein, lacking the first 23 amino acids was found to share the same gel electrophoretic mobility as the parasite-derived CyP protein, suggesting cleavage of a leader sequence. Hybridization of genomic DNA to a full-length cDNA probe indicates that the SmCyP gene is present as a single copy. Immunohistological experiments in conjunction with confocal scanning laser microscopy and immune electron microscopy show that SmCyP is present in abundance in the adult worm as well as in the schistosomula. The function of CyP in the schistosome is presently unclear, but since its ligand, cyclosporin A, has antischistosomal activity, its function is expected to be a vital one.

Amino Acid Isomerases↗
PubMed1994

Genetic analysis of Cuban autosomal dominant polycystic kidney disease kindreds using RFLPs and microsatellite polymorphisms linked to the PKD1 locus.

We report on linkage analysis and haplotype characterization in 12 Cuban families with autosomal dominant polycystic kidney disease (ADPK) using PKD1-linked markers. They included both standard restriction fragment length polymorphisms (26.6., BLu24, and pGGG1) as well as microsatellite polymorphisms (CW2, 16AC2.5, and SM6). All of the examined families were fully informative for genetic diagnosis and no evidence of unlinked families was found. Analysis of two recombination events places PKD1 distal to the marker BLu24 and reduces the size of the region likely to contain the disease gene by approximately 300 kb. The allele frequencies of each marker were similar in the ADPKD and normal populations.

Alleles↗
PubMed1986

Immunoreactive precipitation of C1 inhibitor protein from plasma of normal subjects and of patients with hereditary angioedema after isoelectric focusing.

C1-inhibitor is an acid glycoprotein, isoelectric point 3.5-3.6. Plasma of some patients with a variant form of hereditary angioedema contains high levels of functionless C1-inhibitor-albumin complex with an isoelectric point at 4.5-4.6. Therapy with Danazol, which increases C1-inhibitor levels, does not modify the isoelectric focusing pattern of such protein in patients with hereditary angioedema.

Adult↗
PubMed1978

Variation of hepatic mitochondrial nucleotides in rats contaminated with plutonium-239.

Rats were given 239Pu citrate i.v. and the mitochondria of hepatocytes were studied. A reduction of oxygen consumption per mg protein with time was seen. We have investigated the nucleotides involved in nuclear phosphorylation. After mitochondrial extraction according to Schneider and Hogeboom, [1950], a new method was used for estimating CMP, NAD, 5' AMP, NADP, ADP and GTP. Flavine mononucleotide was not determined. The plutonium content was followed from day 0 to day 65 post injection. Mitochondrial nucleotides were studied on days 5 and 11. On day 5, all nucleotide levels were reduced by 20 to 70% except AMP which increased and GTP which remained constant. On day 11, all nucleotides had decreased by 70 to 100% except NAD which increased by 20 to 30%. The results suggest that plutonium citrate given intravenously has a time dependent effect on the energy metabolism of the liver.

Animals↗
PubMedDate not supplied

Effects of sublingual immunotherapy in patients sensitised to Ambrosia. An open controlled study.

BACKGROUND: Allergy to Ambrosia is a disease of growing importance in Europe. Injective and non-injective immunotherapy have been recognised as safe and effective but no evidence is currently available for sublingual immunotherapy (SLIT) in patients sensitised to Ambrosia. This study was planned to assess the effects and the safety of SLIT in patients clinically sensitised to Ambrosia. METHODS: 19 patients clinically sensitised to Ambrosia and treated with SLIT were compared to 14 patients treated only with drugs. Diary cards with symptoms and drug consumption were filled-in by patients during the pollen season whereas specific nasal challenge and skin prick test were run two months before and after the pollen season. Patients and doctors were also asked to express their subjective assessment about symptoms and drug consumption during the season. RESULTS: SLIT-treated patients had less symptoms and a significantly minor drug intake (p = 0.04) as compared to untreated patients. Nasal challenge test improved significantly in the SLIT group (p = 0.0001) but not in the control group (p = 0.6875) with a significant difference between groups at the end (p = 0.0413) but not at the beginning of the trial (p = 0.213). The decrease in skin reactivity was significant in the control group (p = 0.0186) and highly significant in the SLIT group (p < 0.0001), with no difference between groups (p = 0.2987). Subjective assessment from both patients and doctors was favorable to SLIT (p = 0.0005 for symptoms; p = 0.0019 for drug consumption). Only one minor local side effect was registered during SLIT. CONCLUSIONS: According to our data, SLIT in patients allergic to Ambrosia is safe and able to improve both subjective and objective parameters.

Administration, Sublingual↗
PubMedDate not supplied

[Applied neurophysiology in the deep brain stimulation treatment of multiple sclerosis tremor].

INTRODUCTION: Many patients with multiple sclerosis (MS) develop tremors that may involve one or both lower and/or upper extremities, head and/or voice. In the last few years, chronic high frequency deep brain stimulation of the ventral intermedious (Vim) thalamic nucleus (Vim-DBS, deep brain stimulation) seems to be gradually replacing Vim-thalamotomy in surgical treatment of tremor. The thalamotomy is a destructive procedure of the whole neural components, whereas Vim-DBS has shown to be a selective neurophysiological procedure to block a specific group of neural components, in particular large, fast and low threshold ones. MS is a disease of uncertain etiology characterized by demyelinating plaques in central nervous system. The neurophysiological intraoperative targeting applied to this pathology identifies demyelinated plaques and the functional state of Vim, reduces pitfalls and increases accuracy. Methods included spontaneous and induced multiunit activity recording, semimicroelectrode and tetraelectrode thalamic evoked potentials recording and micro/macro stimulation techniques.

Adult↗