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Biomedical subjects

L Zanetti

Publications and source records attributed to L Zanetti.

At least 19 recordsLinked to original sources
PubMed2000

[The evaluation of the appropriateness of instrumental exams in cardiology. The case of echocardiography].

BACKGROUND: The aim of this study was to evaluate the appropriateness and utility rates of echocardiograms performed in 309 patients in an outpatient clinical setting. METHODS: Data were collected by means of a questionnaire filled in by the cardiologists who performed the examinations. Appropriateness was evaluated according to international guidelines and scored as class I: appropriate, class II: doubtful appropriateness, class III: inappropriate; the exam was deemed useful if it was able to influence the clinical decision-making; normalcy rate was also checked. The relationship between both the referring physicians and motivation of the exam and its appropriateness, and the relationship between appropriateness and both the normalcy rate and utility of the exam were assessed. RESULTS: An echocardiogram was requested by the cardiologist in 46% of patients; the more common reasons for the exam were arterial hypertension (26%), cardiac murmur (18%), palpitations (15%), and known coronary artery disease (10%). The echocardiogram was appropriate (class I) in 25% of patients, doubtfully appropriate (class II) in 39% of patients and inappropriate (class III) in 36% of patients. The appropriateness rate between the cardiologists was similar to that of other prescribing clinicians (p = NS). The highest class III rate was found in patients with hypertension, while the highest class I rate was found in patients with a cardiac murmur (p < 0.01). Normalcy rate was lower in class I than in class II and III exams (p < 0.001). The utility rate was higher in class I (76%) than in class II (13%) and III (< 1%) exams (p < 0.01). CONCLUSIONS: International guidelines can be used effectively and safely to identify (not to prescribe) the useless echocardiograms.

Chi-Square Distribution↗
PubMed1998

[Microalbuminuria, lipid changes and coronary heart disease in non-insulin-dependent diabetics].

BACKGROUND: Microalbuminuria could be a possible coronary risk factor: AIM: To study the association between microalbuminuria, serum lipid levels and coronary heart disease in non-insulin-dependent diabetics. PATIENTS AND METHODS: We studied 104 non-insulin-dependent diabetics, who were separated in four groups according to the presence of microalbuminuria, defined as a 24 h albumin excretion of 30-300 mg/24 h and according the history of coronary artery disease. Total, HDL and LDL cholesterol, triglycerides, alpha, beta, prebeta lipoproteins, lipoprotein (a), apoproteins A and B were measured in all. RESULTS: Twenty patients with and 32 without coronary artery disease had normal albumin excretion and the same number of patients had a urinary albumin 30-300 mg/24 h. All four groups were comparable in terms of metabolic control, nutritional status, blood pressure and creatinine levels. Patients with coronary artery disease had higher urinary albumin excretion than patients without the disease 91 (32-173) and 34 (5-97) mg/24 h respectively p < 0.01. Patients with coronary artery disease and microalbuminuria had higher triglycerides, beta, pre beta lipoproteins, Apo B, Lp(a) and lower Apo B and alpha lipoproteins. This group also had a higher frequency of abnormal pre beta and alpha lipoprotein levels, when compared with coronary patients with normal albumin excretion. In coronary patients there was a positive association between urinary albumin levels and triglycerides (r = 0.24), pre beta lipoproteins (r = 0.27) and Apo B (r = 0.3); there was also a negative association with HDL cholesterol (r = 0.25) and alpha lipoproteins (r = -0.41). CONCLUSIONS: In this group of non-insulin-dependent diabetics, an association among microalbuminuria, abnormal serum lipid levels and coronary artery disease was detected.

Albuminuria↗
PubMed1997

A new transglutaminase-like from the ascidian Ciona intestinalis.

A cDNA clone encoding a transglutaminase (TGase) was isolated from a cDNA library prepared from the larval stage of Ciona intestinalis. The cDNA sequence has an open reading frame encoding a protein of 696 amino acids and is about 36% identical to 11 other TGase sequences. In addition, the critical residues thought to form the catalytic center are conserved. The Ciona TGase (CiTGase) has an extension of 39 amino acids in the NH2-terminal region similar to that reported for keratinocyte TGases. A phylogenetic analysis among other types of TGases demonstrated that CiTGase represents a new type of the enzyme.

Amino Acid Sequence↗
PubMed1996

Transglutaminase activity is related to CAG repeat length in patients with Huntington's disease.

Huntington's disease (HD) is a neurodegenerative disorder associated with CAG repeat expansion. We measured transglutaminase (TGase) activity in lymphocytes from 35 HD patients and from healthy individuals to ascertain whether it was altered in this condition. TGase activity was above maximum control levels in 25% of HD patients; it was correlated with the age of the patient and inversely correlated with the CAG repeat length. These results suggest that: (1) HD could be biochemically heterogeneous, and (2) the length of the CAG repeat expansion/TGase ratio could be important in the manifestation of HD.

Adult↗
PubMed1994

Effects of inhibiting transglutaminase during egg fertilization and development.

Transglutaminase inhibitor (1,3,4,5-tetramethyl-2-[(2-oxopropyl)thio]imidazolium chloride or L-682777) affected the appearance of the fertilization envelope (FE) and subsequent development in Sphaerechinus granularis and Arbacia punctulata in a concentration-dependent manner. Abnormalities were first visible in forming FE's at the lowest concentration (0.001 mM) of the inhibitor used. The wrinkled appearance of FE's suggested that the treatment prevented the I-T transition, whereas the finding of numerous denuded cells and empty FE's indicated that the inhibitor acted by rendering the FE's very fragile. Cell division by the 2-cell stage was also affected by this active-site-directed transglutaminase inhibitor. With 0.05 mM of the inhibitor, about 50% of all cells were polynucleated. In view of earlier findings that other transglutaminase inhibitors can produce abnormalities with regard to FE wrinkling and deranged cell division, it can be suggested that different forms of transglutaminases might be involved at various stages in embryonic development.

Animals↗
PubMed1994

Isolation and characterization of two genes encoding calitoxins, neurotoxic peptides from Calliactis parasitica (Cnidaria).

Among sea anemone neurotoxins, calitoxin, recently isolated from Calliactis parasitica, is a highly toxic peptide of 46 amino acids (aa), whose sequence differs greatly from that of all sea anemone toxins isolated so far. In this study, two genes (clx-1 and clx-2) coding for two highly homologous calitoxins were isolated and characterized from a C. parasitica genomic library. The clx-1 gene encodes the already known calitoxin sequence, named CLX-I, whereas a single bp substitution in the coding region of clx-2 is responsible for a single Glu6-->Lys replacement in a new peptide named CLX-II. The structural organization of the two genes is very similar: two introns and three exons, whose sequences are highly homologous for clx-1 and clx-2 (95% identity). The open reading frame (ORF) of both clx-1 and clx-2 codes for a precursor peptide of 79 aa, whose N-terminus has the feature of a single peptide, while the C-terminus corresponds to the sequences of mature CLX-I and CLX-II. The finding that a pair of basic aa is located upstream from the sequence of both mature toxins strongly suggests that proteolytic events, at specific cleavage sites, are responsible for the release of neurotoxins from their respective precursor molecules.

Amino Acid Sequence↗
PubMed1989

Calitoxin, a neurotoxic peptide from the sea anemone Calliactis parasitica: amino acid sequence and electrophysiological properties.

We have isolated a new toxin, calitoxin (CLX), from the sea anemone Calliactis parasitica whose amino acid sequence differs greatly from that of other sea anemone toxins. The polypeptide chain contains 46 amino acid residues, with a molecular mass of 4886 Da and an isoelectric point at pH 5.4. The amino acid sequence determined by Edman degradation of the reduced, S-carboxymethylated polypeptide chain and tryptic and chymotryptic peptides is Ile-Glu-Cys-Lys-Cys-Glu-Gly-Asp-Ala-Pro-Asp-Leu-Ser-His-Met-Thr-Gly-Thr- Val-Tyr - Phe-Ser-Cys-Lys-Gly-Gly-Asp-Gly-Ser-Trp-Ser-Lys-Cys-Asn-Thr-Tyr-Thr-Ala- Val-Ala - Asp-Cys-Cys-His-Glu-Ala. No cysteine residues were present in the peptide. Similarly to other sea anemone toxins, calitoxin interacts, in crustacean nerve muscle preparations, with axonal and not with muscle membranes, inducing a massive release of neurotransmitter that causes a strong muscle contraction. The low homology of CLX with RP II and ATX II toxins has implications regarding the role played by particular amino acid residues.

Amino Acid Sequence↗
PubMed1989

Molecular forms of immunoreactive gonadotropin-releasing hormone in hypothalamus and testis of the frog, Rana esculenta.

The hypothalamus and the testis of the frog, Rana esculenta, contain gonadotropin-releasing hormone (Gn-RH)-like peptides which are recognized by an antiserum raised against mammalian Gn-RH. Two molecular forms which coelute with synthetic chicken II and salmon Gn-RH from reverse-phase HPLC were distinguished in the hypothalamus. A single peak coeluting with synthetic chicken II Gn-RH was present in the testis.

Animals↗
PubMed1988

Isolation and partial characterization of rhizolysin, a high molecular weight protein with hemolytic activity, from the jellyfish Rhizostoma pulmo.

A new cytolysin has been isolated from the nematocysts of the jellyfish, Rhizostoma pulmo, and named rhizolysin. The hemolysin has a mol. wt of approximately 260,000, a sedimentation coefficient of 10.3 S and is rod-shaped with a calculated axial ratio of about 1:5. It appears to be composed of three subunits with a pI value near 7.8. Rhizolysin shows no phospholipase A activity, nor an induction period for its hemolytic activity and is completely inhibited by sucrose. The optimum pH was 6.75. The mu value calculated from the Arrhenius plot is 5940 cal/mole. Rhizolysin was inhibited by cholesterol and less by sphingomyelin.

Animals↗
PubMed1986

Sinus node pacemaker shift: a phenomenon induced by premature atrial stimulation in man?

The aim of this study was to investigate whether premature atrial stimulation is able to induce a shifting of the sinus node pacemaker. For this purpose we compared, in 18 patients, the curve of sinus node function obtained with Strauss' method with that resulting from the scanning, with premature atrial stimulation, of the first returning cycle following a single premature induced atrial beat. We found that the length of the compensatory phase (zone I) evaluated on the curve resulting from the scanning of the first returning cycle following the single premature induced atrial beat was shorter (15%) than that observed with the original Strauss method. In addition, an inverse relationship between the shortening of the compensatory zone and the estimated sinoatrial conduction time was observed. This result could be accounted for by one of the following explanations: 1) a change in the sinoatrial conduction or in the sinus pacemaker automaticity; 2) sinus node reentry; 3) sinus node pacemaker shift. Even if there is no direct evidence either to prove or to exclude one or more of these explanations, sinus node pacemaker shift seems to be the most convincing explanation.

Adult↗
PubMed1985

Endogenous opioids in marine invertebrates.

A study of the presence of opioids in invertebrates was carried out on 11 species of marine organisms, ranging from sponges to tunicates. Delipidized acid-acetone extracts from whole organisms or dissected organs were assayed by receptor binding assays and radioimmuno assays. The extracts from all species tested were found to contain substances capable of competing in both assays with opioid peptides.

Animals↗
PubMed1984

Different forms of AT-III congenital defect: a study by crossed immunoelectrofocusing.

Antithrombin III (AT-III) deficiency may be due to quantitative or qualitative AT-III reduction. The diagnosis of qualitative disorder is suspected when a discrepancy is found between immunological and functional levels of AT-III. Heterogeneity has been hypothesized in both quantitative and qualitative deficiency of AT-III. A technique based on crossed immunoelectrofocusing (CIEF) was applied to investigate molecular variants of AT-III. 3 families with low functional and immunological levels of AT-III and 1 family with only a low functional AT-III level were investigated. An abnormal AT-III pattern was found with CIEF in the family with suspected qualitative disorder and in 1 of the families with quantitative disorder. The 2 abnormal patterns were different. Thus the use of CIEF AT-III patterns could help to define congenital AT-III deficiencies and could serve as a basis for classification of different forms of AT-III deficiency.

Adult↗
PubMed1982

The hemolytic activity of suberitine.

1. The hemolytic activity of suberitine, a neurotoxic protein isolated from Suberites domuncula, has been examined. 2. The toxin has no phospholipase A activity. 3. The hemolytic activity of suberitine does not exhibit the induction period and is completely inhibited by sucrose. 4. A study of the effect of temperature on the rate of hemolysis shows that suberitine has two values of the critical thermal increment. The optimum pH for the hemolytic activity was 6.0. 5. There was a correlation between the hemolytic and toxic activity.

Animals↗
PubMed1981

[Atrial stimulation and intranodal migration of sinus pacemaker in man (author's transl)].

In order to demonstrate, in man, sinus node pacemaker shift following atrial stimulation, we compared, in 26 patients, the curve of sinus node function obtained with Strauss' method with that resulting by the scanning with premature atrial stimulation of the first returning cycle following either a single premature atrial induced beat (140 ms shorter than the basic cycle) (group A), or a train of 8 consecutive atrial beats induced with a rate slightly faster (10 beats/m) than the control sinus rhythm (group B). Assuming that no changes in sinus pacemaker automaticity or in sinoatrial conduction occur owing to atrial stimulation, curves with the same shape should be observed if the site of the dominant pacemaker remains unchanged: whereas, different lengths of the compensatory phase (zone I) should be expected if an intranodal pacemaker shift occurs. For evaluating the length of the compensatory zone (zone I), we calculate, on the curve of the sinus node function, the mean value of the relation points included in the first third of the reset zone (zone II). According to our results, the length of the compensatory phase (zone I) evaluated on the curve resulting by the scanning of the first returning cycle following either a single premature atrial induced beat (group A), or eight consecutive atrial beats (group B) was shorter than that observed with the original Strauss' method (10% and 18% respectively). However, only in the group B, this difference was statistically significant. In addition, a significant inverse relationship between the shortening of the compensatory zone and the sinoatrial conduction index was also observed. Considering that our results have been corrected in such way as to repeal eventual changes in sinus pacemaker automaticity or sinoatrial conduction following atrial stimulation, the shortening of the compensatory zone, we have observed in our patients, strongly suggests an intranodal sinus pacemaker shift. If we assume that this result could represent an indirect evidence of this phenomenon, some clinical implications may follow: 1) another limitation, in addition to others known (intraatrial conduction delay, sinus arrhythmia, changes in sinus node automaticity, difference between retrograde and antegrade conduction time) could decrease the accuracy of atrial stimulation techniques in the estimation of the sinoatrial conduction time; 2) sinus pacemaker shift following atrial stimulation, may induce an understimulation of the true sinoatrial conduction time; however, according to our results, the error is generally small, so that it does no preclude the usefulness of atrial stimulation techniques in the evaluation of sinoatrial conduction; 3) the more evident and significant shortenings of the compensatory phase occurred with atrial pacing technique: this finding could explain why shorter sinoatrial conduction times are generally observed with Narula's method in comparison with Strauss' method.

Adult↗
PubMed1979

[Diagnostic value of the continuous electrocardiographic monitoring (Holter) and of the electrophysiologic testings in patients with sino-atrial node dysfunction (author's transl)].

A twenty-four hours electrocardiographic recording and an electrophysiological study were performed in 48 patients with sinus bradycardia, 21 of them with symptoms suggesting a sino-atrial dysfunction. Both methods, and independently one each other, were not diagnostic in all symptomatic patients; on the contrary, they showed sinus dysfunction in patients without symptoms related to sino-atrial node dysfunction. These results induce to conclude that the two methods are complementary and that their results must be ever critically accepted, especially when a permanent cardiac pacing is indicated. Because of their not high sensitivity, some patients with sinus dysfunction are not recognised; there-after, the diagnosis is only possible, in these cases, on the base of clinical-signs.

Adult↗