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M Zorzi

Publications and source records attributed to M Zorzi.

At least 19 recordsLinked to original sources
PubMed2002

Are dyspepsia management guidelines coherent with primary care practice?

BACKGROUND: Spontaneous physician behaviour can affect guideline applicability, implementation strategies and application costs, particularly in relation to widespread pathologies chiefly managed by general practitioners (GPs). Of the array of dyspepsia management guidelines, the closest to general practice, partly owing to proposing committee composition, are the European Society for Primary Care Gastroenterology (ESPCG) guidelines. METHODS: To evaluate variability in dyspepsia management among GPs in Padua and divergence in spontaneous prescriptive behaviour from the ESPCG dyspepsia guideline, we prospectively studied the behaviour of 39 GPs over a 3-month period of outpatient activity, through questionnaires on each consultation. Test-group representativeness was preliminarily defined in terms of antisecretory drug expenditure. RESULTS: 1790 forms on dyspepsia-related consultations were studied in a population of 51,193 registered patients; 1264 patients with a history of dyspeptic pathology consulted their GP (19% duodenal ulcer (DU), 9% gastric ulcer (GU), 54% gastro-oesophageal reflux disease (GERD), 32% non-ulcer dyspepsia (NUD), 1% cholelithiasis), while 526 patients presented with symptoms of dyspepsia with no previous gastroscopy (EGDS) (42% were aged <45 years), of whom 42% had twice consulted their GP. Empirical management by prescription of symptomatic drugs was the most common procedure in DU (33%), GU (73%) and NUD (74%) relapses. Helicobacter pylori eradication therapy was prescribed in only 2% of patients with a history of organic or functional dyspepsia. 145 patients with uninvestigated dyspepsia were referred for second-level endoscopy and 43 for H. pylori testing. Forty-four percent of endoscopies prescribed for uninvestigated patients did not comply with the ESPCG guideline; full compliance would have determined a 105% rise in endoscopies. Prescriptive variability between GPs was high (based on the Goodman-Kruskal (0.41, P < 0.001) and Cramer tests (V = 0.51, P < 0.005)) and agreement between observed and expected prescriptions according to ESPCG criteria was as low as V = 0.11. On the basis of the most frequently observed behaviours, we developed three options of the ESPCG guideline and compared them to spontaneous prescriptions. CONCLUSIONS: Highest compliance emerged where the clinical approach for all patients with uninvestigated dyspepsia was symptomatic therapy at first presentation followed by a different attitude at second presentation, setting a higher cut-off age than in the guideline (which in our case proved, on mathematical calculation, to be 55 years).

Adult↗
PubMed2001

Cortical plasticity of spatial stimulus-response associations: electrophysiological and behavioral evidence.

Right-handed subjects tend to respond faster to stimuli presented in the visual hemifield that spatially corresponds to the responding hand. In a typical Simon task, response is based on a non-spatial salient feature of the stimulus (e.g. color) whereas its position must be ignored. However, the spatial position of the stimulus interferes with the processing of the salient characteristic. Subjects are significantly faster when stimulus side and response side correspond (corresponding condition) than when they do not (non-corresponding condition). We have previously shown with behavioral experiments that, when subjects practice reversed contingencies (that is, spatially incompatible trials) in a session preceding the Simon task, they show a long-term retention of these associations, resulting in the disappearance of the latency cost typically observed in non-corresponding trials. Here we show, by means of the lateralized readiness potential, that the neural correlate of such behavioral plasticity is an increase in premotor cortex activation during preparation of non-corresponding responses. This effect showed a marked left-right asymmetry which suggests an important role of subjects' handedness. Our results demonstrate that humans can learn in a single session to reverse relatively stable stimulus-response associations.

Adult↗
PubMed2001

Storage and retrieval of addition facts: the role of number comparison.

It is proposed that arithmetical facts are organized in memory in terms of a principle that is unique to numbers--the cardinal magnitudes of the addends. This implies that sums such as 4 + 2 and 2 + 4 are represented, and searched for, in terms of the maximum and minimum addends. This in turn implies that a critical stage in solving an addition problem is deciding which addend is the larger. The COMP model of addition fact retrieval incorporates a comparison stage, as well as a retrieval stage and a pronunciation stage. Three tasks, using the same subjects, were designed to assess the contribution of these three stages to retrieving the answers to single-digit addition problems. Task 3 was the addition task, which examined whether reaction times (RTs) were explained by the model; Task 1 was a number naming task to assess the contribution of the pronunciation stage; Task 2 was a magnitude comparison task to assess the contribution, if any, of the comparison stage. A regression equation that included just expressions of these three stages was found to account for 71% of the variance. It is argued that the COMP model fits not only the adult RT data better than do alternatives, but also the evidence from development of additional skills.

Adult↗
PubMed2000

A single calibration graph for the direct determination of ascorbic and dehydroascorbic acids by electrogenerated luminescence based on Ru(bpy)(3)2+ in aqueous solution

Ascorbic (H2A) and dehydroascorbic (DA) acids were for the first time directly determined in a single chromatographic run by means of the tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)(3)2+) based electrogenerated chemiluminescence (ECL) detection. For the first time, it was demonstrated that DA, a nonelectroactive compound, is ECL active and is responsible for the ECL behavior of H2A. This fact, together with the lack of a DA standard, suggested the use of a calibration graph obtained for H2A, for determining both analytes. The proven ECL activity of DA, together with literature data relative to the standard redox potentials of the different species coming from H2A, led to a reconsideration of the proposed ECL reaction mechanism for H2A. The role of the OH- ion in the reaction mechanism of the two analytes appeared to be crucial. H2A and DA could be separated by a suitable C18-reversed-phase HPLC column using an aqueous 30 mM H3PO4 solution as the mobile phase. The optimal ECL response was achieved by polarizing the working electrode at 1.150 Vvs SCE (standard calomel electrode) (oxidation diffusion limiting potential for both H2A and Ru(bpy)(3)2+). The Ru(bpy)(3)2+ solution, at pH 10 for carbonate buffer, was mixed to the eluent solution in a postcolumn system, obtaining, still at pH 10, the final 0.25 mM Ru(bpy)(3)2+ concentration. The detection limit found for the two analytes was 1 x 10(-7) M. The method was successfully applied to the determination of the analytes in a commercially available orange fruit juice.

Journal Article↗
PubMed2000

Response strategies and the Simon effect.

The study investigated whether the Simon effect, and its facilitation and interference components, shows up in reaction time (RT) or in movement time (MT), depending on the response strategy. Experiment 1 replicated a study by Hietanen and Rämä. Subjects had to press one of two lateralised keys in response to one of two stimuli. The stimuli were presented in the center (neutral condition) or to the left or right side (corresponding or non-corresponding conditions). To press the response key, a reaching movement was necessary, and both RT and MT were recorded. One group of subjects showed an RT facilitation effect and an MT interference effect. Another group of subjects showed both MT facilitation and MT interference effects. It was hypothesized that the two groups used different response strategies. In Exps. 2 and 3, the subjects were explicitly instructed to use the two strategies that were hypothesized for Exp. 1. The results showed that whether facilitation and interference manifest themselves in RT or MT depends on the response strategy adopted by the subjects.

Humans↗
PubMed2000

The role of long-term-memory and short-term-memory links in the Simon effect.

In Experiment 1, children performed a Simon task after a spatially compatible or incompatible task. Results showed a Simon effect after the spatially compatible task and a reversed Simon effect after the spatially incompatible task. In Experiments 2-5, an identical procedure was adopted with adult participants, who performed the Simon task immediately after, a day after, or a week after the spatial compatibility task. Experiment 6 established a baseline for the Simon effect. Results showed a Simon effect after the spatially compatible task and no Simon effect or a reversed Simon effect after the spatially incompatible task. A modified version of the computational model of M. Zorzi and C. Umiltà (1995) was used to compare possible accounts of the findings. The best account exploits 2 types of short-term-memory links between stimulus and response and their interaction with long-term-memory links.

Adult↗
PubMed2000

Effects of cryopreservation on progesterone-induced ion fluxes and acrosome reaction in human spermatozoa.

The present study evaluated the effects of cryopreservation on progesterone-induced variations of calcium ion concentration [Ca(2+)](i), plasma membrane potential and acrosome reaction in human spermatozoa. Spermatozoa from 10 fertile donors were divided in two equivalent aliquots, one used as control (fresh spermatozoa) and the other used after freezing-thawing. Measurement of spermatozoa [Ca(2+)](i) before and after freezing-thawing showed a significant reduction of basal [Ca(2+)](i) in thawed spermatozoa (P < 0.01). Progesterone induced a rise of [Ca(2+)](i) both in fresh and thawed spermatozoa with a significant reduction after freezing-thawing (P < 0.01). The monitoring of sperm plasma membrane potential demonstrated that progesterone induced plasma membrane depolarization in fresh spermatozoa that was absent in thawed spermatozoa. The inhibitory effects of freezing-thawing on progesterone induced [Ca(2+)](i) and plasma membrane potential variations in human spermatozoa were closely related to the inhibition of the acrosome reaction. In conclusion the present study demonstrates that freezing-thawing procedures reduce the responsiveness of human spermatozoa to progesterone in terms of [Ca(2+)](i) rise and completely inhibit its effects on plasma membrane potential variations, thus supporting the hypothesis that freezing-thawing procedures may differently modify the plasma membrane receptors for progesterone in human spermatozoa which are known to express at least two receptors for this steroid in their plasma membrane.

Acrosome Reaction↗
PubMed2000

Serial processing in reading aloud: no challenge for a parallel model.

K. Rastle and M. Coltheart (1999) challenged parallel models of reading by showing that the cost of irregularity in low-frequency exception words was modulated by the position of the irregularity in the word. This position-of-irregularity effect was taken as strong evidence of serial processing in reading. This article refutes Rastle and Coltheart's theoretical conclusions in 3 ways: First, a parallel model, the connectionist dual process model (M. Zorzi, G. Houghton, & B. Butterworth, 1998b), produces a position-of-irregularity effect. Second, the supposed serial effect can be reduced to a position-specific grapheme-phoneme consistency effect. Third, the position-of-irregularity effect vanishes when the experimental data are reanalyzed using grapheme-phoneme consistency as the covariate. This demonstration has broader implications for studies aiming at adjudicating between models: Strong inferences should be avoided until the computational models are actually tested.

Attention↗
PubMed1995

A computational model of the Simon effect.

Even though stimulus location is task irrelevant, reaction times are faster when the location of the stimulus corresponds with the location of the response than when it does not. This phenomenon is called the Simon effect. Most accounts of the Simon effect are based on the assumption that it arises from a conflict between the spatial code of the stimulus and that of the response. In this paper a computational model of this hypothesis is presented. It provides a computationally explicit mechanism of the Simon effect. Consistent with human performance, the model provides reaction times that indicate both an advantage for the ipsilateral, corresponding response (i.e., facilitation) and a disadvantage of the contralateral, noncorresponding response (i.e., inhibition). In addition, the model accounts for the fact that the size for the effect depends on task difficulty.

Attention↗
PubMed1995

Functional and structural characteristics of human epididymal spermatozoa retrieved by transcutaneous aspiration.

The present paper describes the development of a simple, repeatable technique for transcutaneous aspiration of epididymal spermatozoa in patients with inoperable excretory azoospermia. Some functional and structural parameters of the retrieved spermatozoa were also evaluated. Epididymal spermatozoa from patients and ejaculated spermatozoa from fertile donors showed similar percentages of acrosome-reacted cells after incubation for 6 or 15 h in capacitating medium. Penetration of zona-free hamster oocytes, expressed as the percentage of penetrated ova, was significantly lower (p < 0.01) for spermatozoa from patients than for ejaculated spermatozoa from fertile donors. The percentage of epididymal spermatozoa with stable nuclei in sodium dodecyl sulphate was lower (p < 0.001) than for ejaculated spermatozoa from fertile donors. A positive linear correlation (r = 0.74, p < 0.005) was evident between the oocyte penetration rate and the percentage of spermatozoa with stable nuclei. In conclusion the percutaneous retrieval of epididymal spermatozoa in excretory azoospermia allows collection of motile spermatozoa, which can be evaluated for their structural and functional characteristics before repetition of the technique for retrieval of spermatozoa for assisted fertilization techniques.

Adult↗
PubMed1993

[Not Available].

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History, Ancient↗
PubMed1992

Sperm nuclear instability and staining with aniline blue: abnormal persistence of histones in spermatozoa in infertile men.

During mammalian spermiogenesis, replacement of the somatic histones by basic proteins, the protamines, allows normal sperm nuclear condensation. In this study we have evaluated the degree of chromatin compaction in spermatozoa from 191 infertile subjects, affected by different testicular disorders, compare with that in 50 fertile sperm donors (controls). In infertile men, there was a higher percentage of unstable spermatozoa after incubation with sodium dodecyl sulphate (SDS) and of stained spermatozoa after staining with aniline blue (P less than 0.001 vs. controls). Furthermore, a positive linear correlation was found between SDS-unstable spermatozoa and stained spermatozoa (P less than 0.001), suggesting that sperm instability was related to a defect in histone-replacement by sperm-specific nucleoproteins, protamines. When the patients were considered according to pathology, high sperm nuclear instability and a high percentage of stained spermatozoa were detected in groups affected by varicocele, idiopathic infertility and in patients with a history of unilateral cryptorchidism. In the latter group the same alterations were observed even when the cryptorchid testis had been removed during surgery. In the group with a past history of mumps orchitis these parameters did not show any difference when compared with controls.

Adult↗
PubMed1991

Evidence for the involvement of sperm angiotensin converting enzyme in fertilization.

Recently it has been observed that ejaculated human sperm possess high angiotensin converting enzyme (ACE) activity and that this enzyme is released during the process of capacitation. This observation raises the possibility that ACE may be involved in the fertilization process. To verify this hypothesis, we tested the effects of a potent ACE inhibitor, Captopril, on acrosome reaction induced by capacitating medium (3.5% HSA-added BWW) and on ability of human capacitated spermatozoa to penetrate zona-free hamster oocytes. Addition of Captopril (100 nmol l-1) modified neither sperm motility nor viability at any time considered, but significantly reduced the acrosome reaction percentages of sperm incubated in capacitating medium. Furthermore, Captopril significantly reduced the percentage of penetrated oocytes. The mean penetration rates both in the absence and presence of Captopril were 65.5 +/- 4.9% and 26.9 +/- 2.3% (P less than 0.001) respectively. These findings provide evidence that sperm release of ACE during capacitation may have a physiological role in the regulation of the mechanisms that allow sperm acrosome reaction and thus fertilizability.

Acrosome↗
PubMed1989

Evidence for a dopaminergic involvement in the inhibitory effect of alpha human natriuretic peptide on prolactin in man.

Recently, it has been suggested that Atrial Natriuretic Peptides (ANP), as well as peripheral hormones, may have a role as central neurotransmitters or neuromodulators, and in humans it has been observed that alpha human ANP inhibits prolactin secretion. In this study, on 12 normal adult males, we evaluated the effects of ANP on the prolactin release induced by TRH and by the dopaminergic blocker sulpiride. Alpha-hANP administration was followed by a significant fall of prolactin plasma levels but did not influence TRH-induced prolactin response. Nevertheless, sulpiride-induced prolactin secretion was significantly lower after Alpha-hANP administration than after placebo pre-treatment (p values ranging between 0.01 and 0.001). Our results suggest that in man Alpha-hANP has no direct influence on lactotrope cells in inhibiting prolactin secretion, but seems to involve activation of the hypothalamic dopaminergic system.

Adult↗
PubMed1984

Lymphadenopathic and oropharyngeal Kaposi's sarcoma in a drug addict with acquired immunodeficiency syndrome. Immunological abnormalities in peripheral blood and lymphoid tissue.

Lymphocyte subsets were analyzed in peripheral blood and lymph nodes from a drug-addict with acquired immunodeficiency syndrome (AIDS) presenting with disseminated lymphadenopathic and oropharyngeal Kaposi's sarcoma. At the onset of disease, hypergammaglobulinemia, increase of OKT8+ T cell subset and reversal of OKT4/OKT8 ratio were found in the blood. At the same time, lymph nodes displayed, besides Kaposi's sarcoma, marked follicular hyperplasia, plasmocytosis and increase of OKT8+/Leu 2a+ T cells within follicular centers. These results are interpreted to indicate that at an early stage of disease the major tissue alterations took place within follicular centers and consisted of both B cell activation and T suppressor cell reaction. These changes correlated with immunological abnormalities observed in peripheral blood. Immunohistochemical investigation of lymphoid tissue may be useful to detect AIDS patients at an early stage.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Progesterone induces capacitation in human spermatozoa.

Mammalian sperm acrosome reaction is a prerequisite for oocyte fertilization, and to date the mechanisms regulating this event are still unclear. Recent studies have demonstrated that human follicular fluid is able to induce an influx of extracellular calcium and acrosome reaction in capacitated spermatozoa. More recently these effects have been attributed to progesterone. The results of our study demonstrated that progesterone is able to trigger the capacitation, acrosome reaction, and fertilizability in human spermatozoa through a calcium mediated mechanism, suggesting a clinical use of this steroid in the treatment of spermatozoa for the different techniques of assisted fertilization.

Acrosome↗