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Biomedical subjects

A Mazza

Publications and source records attributed to A Mazza.

At least 55 records · Page 3Linked to original sources
PubMed1997

Blood pressure, serum cholesterol and nutritional state in Tanzania and in the Amazon: comparison with an Italian population.

OBJECTIVE: To confirm that westernization of dietary habits represents a stimulus for the expression of cardiovascular risk. DESIGN: Three representative age- and sex-matched samples of general populations of three continents were compared cross-sectionally by analysis of variance. PARTICIPANTS: In total 1110 subjects aged 22-89 years, divided into three groups (370 from Tanzania and Uganda, 370 from the Amazonian region of Brazil, and 370 from northern Italy; 111 men and 259 women in each group). RESULTS: The blood pressure of Africans eating a low-salt fish and vegetable' diet was lower than those of Brazilians, whose diet was based on cereals and meat, and highly urbanized Italians. The systolic blood pressure was correlated to the body mass index for all three populations, but with age only for the Brazilians and Italians. The total cholesterol level and body mass index, both of which are low among Africans, increased progressively with increasing economic level. CONCLUSIONS: Transition from a rural to an urbanized lifestyle is accompanied by a rise in the main cardiovascular risk factors; the present data also show that environmental rather than racial factors have a crucial impact on the risk pattern of populations.

Adult↗
PubMed1997

[Comparison of anti-arrhythmic therapy guided by the transesophageal electropharmacologic test and emperic therapy in the prophylaxis of atrial fibrillation recurrence].

BACKGROUND: There is no written data about the efficacy of transesophageal electropharmacologic test (TEPT) to guide antiarrhythmic therapy in the prophylaxis of paroxysmal atrial fibrillation (PAF) recurrences. Aim of this study was to assess the efficacy of TEPT compared to empiric treatment in the prophylaxis of PAF. METHODS: One-hundred-sixty patients (pts) with previous episodes of PAF were randomized in two groups: Gr A (90 pts) was submitted to basal transesophageal electrophysiologic study (BTES); Gr B (70 pts) was submitted to randomized empiric antiarrhythmic therapy with flecainide (F), propafenone (P) and sotalol (S). The end-points of stimulation protocol in Gr A were the induction of sustained atrial fibrillation (SAF)- > or = 1 min duration- or the end of protocol. SAF was inducible in 68/90 pts (Gr A1) while it was not in 22/90 pts (Gr A2). Pts in Gr A1 were subsequently submitted to TEPT at steady-state of F, P or S randomized in first choice. Pts responders (R) (SAF non inducible) were submitted to TEPT with other antiarrhythmic drugs randomized in second choice: R were followed-up with the same drug in chronic oral assumption, while non responders (NR) were submitted to TEPT with the last drug and followed-up with the same drug both in R and NR case. The same stimulation protocol was employed in TEPT as in BTES. Pts in Gr A2 withdrew from the study. During follow-up all-pts were submitted to periodic specialist examinations every three months. In case of PAF recurrence pts withdrew from the study. RESULTS: Mean follow-up duration in the study population was 17.5 +/- 8.5 months. One-hundred-eight TEPT were performed in Gr A1: 36 tests with F, 40 with P and 32 with S. Twenty pts were R with F (55% of tests) and 17 finished the follow-up, 22 pts were R with P (55% of tests) and 16 finished the follow-up, 19 pts were R with S (59% of tests) and 15 finished the follow-up; 3 pts with F, 2 pts with P and 2 pts with S were NR in last choice and finished the follow-up. In Gr A1 61/68 pts (90%) were R and 55/68 (81%) finished the follow-up (13 pts withdrew from the study). In Gr B (70 pts) 23 pts were randomized to F and 20 finished the follow-up, 24 pts were randomized to P and 20 finished the follow-up, 23 pts were randomized to S and 20 finished the follow-up (10 pts withdrew from the study). PAF recurrences during follow-up in Gr A1 were in 15/55 pts (27%): 9/48 pts (19%) R and 6/7 pts (86%) NR, and in Gr B in 41/60 pts (68%). Gr A1 vs Gr B p < 0.001. Univariate and multivariate statistical analysis showed the empiric treatment as the only variable with high predictive value for PAF recurrences (risk ratio 1.53). PPV and NPV of TEPT were respectively 86 and 81%. CONCLUSIONS: TEPT-guided antiarrhythmic therapy in the prophylaxis of PAF recurrences seems to be an effective method in predicting the efficacy of the chronic antiarrhythmic therapy, when compared to the empiric treatment. The non inducibility of SAF at TEPT would have a high predictive value for event-free follow-up.

Anti-Arrhythmia Agents↗
PubMed1997

[Late ventricular potentials and acute myocardial infarction].

BACKGROUND: The presence of late ventricular potentials was evaluated in a group of patients following acute myocardial infarction hospitalised in our division. MATERIALS AND METHODS: Recordings were made between the 10th and 12th day of the pathology. The criteria for positivity were the presence of three parameters: QRSD > or = 114 msec, LAS 40 > or = 38 msec, RMS 40 < or = 20 mv. These were present in 21 patients (18 males and 3 females). Inferior acute myocardial infarction (AMI) was found to be present in 15 cases, anterior AMI in 4 cases and AMI with an unspecified localisation in 2 cases. The mean duration of qrsd was 122 msec, the mean duration of low amplitude potentials (LAS 40) were 53.5 msec, the mean amplitude of the last 40 msec (RMS 40 was 8.9 mv). CONCLUSIONS: In conclusion, the authors affirm that late potentials were present in the majority of patients with inferior AMI and the search for the latter represents an important stage in the post-AMI prognostic stratification. Delta is the positive correlation between late potentials and ventricular tachycardia in postinfarction. This non-invasive test is comparable to electrophysiological induction tests in terms of predictive capacity of arrhythmic event and/or sudden death.

Aged↗
PubMed1996

Impaired glucose tolerance and its co-variates among 2079 non-diabetic elderly subjects. Ten-year mortality and morbidity in the CASTEL study. CArdiovascular STudy in the ELderly.

This study evaluated the role of impaired glucose tolerance (IGT) as a risk factor in a general population of 2079 non-diabetic elderly subjects. The 10-year cardiovascular morbidity was similar in normal and IGT subjects. Mortality was greater in IGT, but the Cox equations of the hazard rate were different in younger and older subjects: age, sex, lung function (forced expiratory volume in 1 s, FEV1), serum uric acid, IGT and proteinuria were predictors of overall mortality in the age class 65-79 years, while only the first 4 were associated with cardiovascular mortality. The same four items also predicted overall survival in subjects over 79 years old, while only age and uric acid were predictors of cardiovascular mortality. In older subjects, total cholesterol showed an inverse predictive value. Hyperuricaemia (> 6.4 mg/dl) and proteinuria did predict mortality in normal but not in IGT subjects, while reduced FEV1 (< 60% theoretical) was predictive in all. In 65-79-year old subjects IGT predicted mortality provided that FEV1 was normal, while in those 380 years old IGT was not a predictor. These interrelationships should be taken into account to better understand the factors underlying mortality.

Aged↗
PubMed1996

[Hypertension secondary to multiple malignant paragangliomas].

We describe a case of severe hypertension, due to multiple malignant norepinephrine secreting paragangliomas. Neuroendocrine system tumours are responsible for 0.1-0.5% cases of hypertension. Their extra-adrenal localisation is about 10%. Only 20% of paragangliomas are catecholamine secreting, and causing a syndrome similar to that of pheochromocytoma. In our patient the diagnosis of retroperitoneal multiple paragangliomas was made two years after the beginning of the typical symptoms. At surgery 6 paragangliomas were removed; some vascular and muscular structures (inferior vena cava, ileopsoas) were infiltrated. A radiotherapy treatment was conducted for a total dose of 55.8 Gy. Immediately after the operation blood pressure decreased, but the administration of alpha and beta blockers was required to reach normotension. This treatment was confirmed at six months follow-up, in consideration of the persistently high norepinephrine plasma levels.

Adult↗
PubMed1995

The CryIA(c) receptor purified from Manduca sexta displays multiple specificities.

The kinetic binding characteristics of four Bacillus thuringiensis CryI insecticidal crystal proteins to a Cry-binding protein, purified from Manduca sexta brush-border vesicles, were analyzed by an optical biosensor. This 120-kilodalton binding protein, previously determined to be aminopeptidase N, was converted to a 115-kilodalton water-soluble form by removing the attached glycosylphosphatidylinositol anchor with phospholipase C. The solubilized form recognized the three major subclasses of CryIA toxins but not CryIC even though all four CryI proteins are toxic to larvae of M. sexta. CryIA(a) and CryIA(b) toxins bound to a single site on the solubilized aminopeptidase N molecule whereas CryIA(c) bound to two distinct sites. Apparent kinetic rate constants were determined for each binding reaction. All three CryIA toxins exhibited moderately fast on rates (approximately 10(-5) M-1 s-1) and a slow reversible off rate (approximately 10(-3) s-1). Although the second CryIA(c)-binding site retained a moderately fast association rate, it was characterized by a rate of dissociation from the amino-peptidase an order of magnitude faster than observed for the other CryIA-binding sites. CryIA(c) binding to both sites was strongly inhibited in the presence of N-acetylgalactosamine (IC50 = 5 mM) but not N-acetylglucosamine, mannose, or glucose. CryIA(a) and CryIA(b) binding were unaffected in the presence of the same sugars. Our results serve to illustrate both the complexity and the diverse nature of toxin interactions with Cry-binding proteins.

Acetylgalactosamine↗
PubMed1995

Codon-based combinatorial alanine scanning site-directed mutagenesis: design, implementation, and polymerase chain reaction screening.

Combinatorial alanine scanning mutagenesis is a powerful tool for the exploration of protein structure-function relationships. Unfortunately, combinatorial alanine replacement of multiple residues using standard site-directed mutagenesis is restricted to a subset of amino acids. To circumvent this limitation, an efficient procedure for combinatorial site-specific replacement by alanine of any residue in a given protein sequence has been established. The method, which involves simple procedures and commonly used materials, is based upon the use of codon-based mutagenesis. A defined ratio of alanine to wild-type codon was introduced at each predetermined triplet using the "column-splitting" technique during oligonucleotide synthesis. High-throughout genetic screening of mutant libraries was facilitated by the incorporation of diagnostic restriction sites at targeted codons followed by a PCR-based screening procedure. The method was tested on a set of 13 residues located at the interface between the variable domains of a Fab fragment of an antibody. The occurrence of alanine substitution was found to be comparable to the statistically predicted distribution.

Alanine↗
PubMed1995

Kinetics of Bacillus thuringiensis toxin binding with brush border membrane vesicles from susceptible and resistant larvae of Plutella xylostella.

An optical biosensor technology based on surface plasmon resonance was used to determine the kinetic rate constants for interactions between the CryIA(c) toxin from Bacillus thuringiensis and brush border membrane vesicles purified from susceptible and resistant larvae of diamondback moth (Plutella xylostella). CryIA(c) association and dissociation rate constants for vesicles from susceptible larvae were determined to be 4.5 x 10(3) M-1 s-1 and 3.2 x 10(-5) s-1, respectively, resulting in a calculated affinity constant of 7 nM. CryIE toxin did not kill susceptible or resistant larvae and did not bind to brush border vesicles. Contrary to expectations based on previous studies of binding in resistant P. xylostella, the binding kinetics for CryIA(c) did not differ significantly between susceptible larvae and those that were resistant to CryIA(c). Determination of the number of CryIA(c) receptors revealed an approximately 3-fold decrease in total CryIA(c) receptor numbers for resistant vesicles. These results suggest that factors other than binding may be altered in our resistant diamondback moth strain. They also support the view that binding is not sufficient for toxicity.

Animals↗
PubMed1995

[The reduction of respiratory function is an independent risk factor in the elderly].

The predictive value of the impairment of lung function and cigarette smoking has been evaluated in 2080 elderly subjects aged > or = 65 years included in the CASTEL (Cardiovascular Study in the Elderly). Some common risk factors, as well as forced expiratory volume, vital lung capacity, and Tiffenau index have been examined with Cox analysis. The 10-year survival equation was as follows: [formula: see text] In disagreement with other studies, in our survey smoking was not a predictor of mortality, although it was able to reduce survival by reducing respiratory function.

Age Factors↗
PubMed1995

Incidence and complexity of ventricular ectopy during Holter monitoring in patients with exercise-induced myocardial ischemia and normal or mildly reduced left ventricular function.

We aimed to assess the relationship between frequent and complex ventricular ectopy by continuous electrocardigraphic 24-hours Holter monitoring in patients with coronary artery disease and inducible ischemia during exercise procedures. We investigated 609 consecutive patients. They were referred for chest pain (28% with a previous myocardial infarction, older than 6 months). In all population patients radionuclide ventriculography showed a global normal or mildly reduced left ventricular function (ejection fraction > 45%). All patients showed exercise-induced myocardial ischemia (ST depression) and exercise thallium-201 reversible defects. During Holter monitoring, in study population, divided according to incidence of premature ventricular complexes (PVC), we found a higher prevalence of complex ventricular arrhythmias (CVA) (bigeminy, couplets, ventricular tachycardia, multiformity) in patients with high incidence of PVC. The relationship between frequent and complex ventricular ectopy has been observed also during ischemic ST shifts occuring during 24-hours monitoring. In contrast, the R on T phenomenon was not related to incidence of PVC. Therefore, in patients with exercise-induced myocardial ischemia and global normal or mildly reduced left ventricular function there is a relationship between frequent and complex ventricular ectopy, as previously suggested in CAD patients with depressed left ventricular function.

Adult↗
PubMed1995

[A comparison between flecainide and sotalol in the prevention of recurrences of paroxysmal atrial fibrillation].

OBJECTIVES: Aim of the present study was to assess the efficacy and safety of flecainide (F) and sotalol (S) for the prevention of recurrences of paroxysmal atrial fibrillation (PAF). METHODS: Sixty-six patients with PAF (> or = 3 episodes of atrial fibrillation in the last year) in sinus rhythm, were randomized to pharmacological oral treatment with F (20 patients-Group A), with S (20 patients-Group B) and placebo (P) (26 patients-Group C). During the follow-up (one year duration) were evaluated on I, III, VI and XII months the number and tolerance of the atrial fibrillation recurrences, cardiac and/or noncardiac side effects. The patients with more than two recurrences in the same follow-up interval withdrew from the study. In each patient 14 clinical and laboratory variables were evaluated. RESULTS: After 12 months were arrhythmia-free respectively 70% of Group A patients, 60% of Group B patients, 27% of Group C patients. Univariate analysis showed that treatment with F was related to decrease of atrial fibrillation recurrences (one recurrence 67%, two recurrences 81%, three recurrences 81%), treatment with S was related to decrease of recurrences (two recurrences 59%); the variable most significantly related to the risk of arrhythmia recurrence is the higher value of basal cardiac rate (one recurrence t = 2.15, two t = 2.22, three t = 2.96, four t = 2.06). There was not statistically significant difference in maintenance of sinus rhythm at the end of the follow-up between the groups of patients on F and S (p = 0.163); treatment efficacy was significantly higher than P (p = 0.002). Multivariate analysis showed that treatment with F and S decreases the risk of arrhythmia recurrence respectively of 85% and 76% versus placebo at the end of the follow-up. The incidence of cardiac and/or noncardiac side effects was not clinically significant. CONCLUSION: F and S are both effective and safe for prevention of PAF, with 70% and 60% respectively of patients arrhythmia-free after 12 months of treatment. Side effects were common, but clinically significant adverse events were uncommon. A higher value of basal cardiac rate was predictive of atrial fibrillation recurrences in the patients during treatment.

Adult↗
PubMed1994

Stable immobilization of lipid vesicles for kinetic studies using surface plasmon resonance.

In order to study the kinetics of binding between membrane vesicle surface receptors to the lepidopteran insecticidal toxins from Bacillus thuringiensis using surface plasmon resonance, we have developed a technique to immobilize membrane vesicles purified from the brush border of dissected guts from the lepidopteran insect pest Choristoneura fumiferana. Two methods using immobilized immunoglobulins against either avidin or biotin were successful in achieving stable immobilization of the vesicles (> 1.5 h). Specificity of the immobilized receptors exposed on the vesicle surface was demonstrated, in part, by the inability of bovine serum albumin to bind to the immobilized brush border membrane vesicles. Homologous and heterologous competition experiments further demonstrated specific binding of trypsin-activated CryIA(c) toxin to the cell-surface receptors on the vesicles. Kinetic rate constants for activated cryIA(b) toxin binding to brush border vesicles were determined, revealing the presence of a high-affinity receptor on the surface of the immobilized brush border membrane vesicles.

Animals↗
PubMed1994

Specificity domain localization of Bacillus thuringiensis insecticidal toxins is highly dependent on the bioassay system.

The Bacillus thuringiensis crylA(a) and crylA(c) gene specificity regions were probed by creating and testing hybrid toxins both in vivo and in vitro against cultured insect cells or dissociated midgut epithelial cells. Toxin threshold dose determinations revealed that CrylA(c) is highly active against cultured Choristoneura fumiferana cells (CF-1) whereas CrylA(a) is nontoxic. In live insect bioassays, a reversed order of toxicity was observed. Hybrid analysis revealed that the CrylA(c) toxicity-determining region is located between codons 258 and 510. Two smaller subsections of this region (residues 258-358 and 450-510) were able to confer toxicity, although at lower levels, and one region (358-450) was present where progressive substitutions of crylA(a) with crylA(c) sequences had no effect. Exchanging the non-homologous N-terminal regions of CrylA(c) with CrylE suggested that the N-terminus does not play a role in specificity. One hybrid clone, MP80, displays a 99.3% homology to CrylA(b) but shows an 800-fold increase in toxicity to CF-1 cells relative to that shown by CrylA(b). Direct comparison between live Bombyx mori bioassays and a newly developed in vitro lawn assay using dissociated midgut epithelial cells from the same insect revealed striking differences in toxicity. The toxicity-determining region for B. mori larvae was determined to be between codons 283 and 450, although the 450-620 codon region may exert an influence on toxicity. In general, native or hybrid toxins showing little or no insect intoxication were very active against the epithelial cells, suggesting that factors other than toxin amino acid sequence play an important role in determining toxin specificity.

Amino Acid Sequence↗
PubMed1994

The use of antibiotics in the treatment and prevention of infection in HIV-infected children.

Children with HIV infection have an unusual susceptibility to bacterial infection, related to several immune abnormalities. Selection of initial antibiotic therapy must be individualized in these children. Patients with community-acquired disease are most likely to have infection by polysaccharide-encapsulated bacterial organism, most commonly Streptococcus pneumoniae and less frequently by Haemophilus influenzae type b. If it is possible to treat the patients at home, the use of amoxicillin-clavulanic acid might be appropriate. Other authors propose management with parenteral ceftriaxone because of the better compliance and the malabsorption. In hospitalized patients, concern for Gram-negative enteric pathogens other than polysaccharide-encapsulated organisms requires initial therapy with a third-generation cephalosporine in combination with an aminoglycoside. Trimethoprim-sulfamethizole is the most common drug used in HIV-infected children because it is recommended for the initial therapy and for prophylaxis of pneumocystis carinii pneumonia, which occurs in as many as 42% of these children.

AIDS-Related Opportunistic Infections↗
PubMed1994

Paediatric AIDS: a new child abuse.

In relation to youth rights, a new view has been created in recent decades that is included in the fundamental law of the child: the recognition of the right to education and the chance to develop a mature personality capable of creativity and liberty. Because of HIV infection it is very important to pay particular attention to the rights of the seropositive child and children born to seropositive mothers, which may be hampered not only in developing countries but also in the industrial world. HIV-affected children and their families are becoming abused and at high risk of becoming abused and this encroaches upon youth rights. As a consequence, in 1991 the Italian Society of Paediatrics issued a "Charter for the rights of seropositive children", which became an important document for all health care and social workers who deal with HIV-affected children. In this paper, we also consider the impact of HIV infection on the three main rights of children: the right to live, the rights of security and the rights of socialization.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Effect of two different therapeutic approaches on total and cardiovascular mortality in a Cardiovascular Study in the Elderly (CASTEL).

Although limited numbers of elderly subjects have occasionally been included in population-based studies, only a few studies have been conducted specifically on elderly hypertensives, and practically none at a population level. We studied 655 hypertensive subjects from a cohort of 2,254 elderly subjects. The intervention consisted of the creation of a Hypertension Outpatients' Clinic under our auspices but with complete co-operation from general practitioners, randomizing the identified hypertensive patients into pre-established therapeutic drug regimens, and early follow-up recording of mortality for 7 years. The drugs used were clonidine (n = 61), nifedipine (n = 146) and the fixed combination of atenolol+chlorthalidone (n = 144); 304 subjects underwent "free therapy" by their personal physicians without any special intervention. There were 1,404 normotensive subjects. Overall 7-year follow-up mortality was 34.9% in the hypertensive subjects receiving "free therapy", 22.5% in those receiving "special care", and 24.2% in the normotensives. Cardiovascular mortality was respectively 23.7%, 12.2%, and 12.0%. Overall and cardiovascular annual cumulative mortality were significantly lower in the << special therapy >> than in the << free therapy >> group. The fixed combination of atenolol and chlorthalidone reduced mortality below that of the normotensives, independent of other cardiovascular risk factors.

Aged↗
PubMed1993

Predictors of mortality in very old subjects aged 80 years or over.

We studied 318 subjects aged 80 years of over included in the Cardiovascular Study in the Elderly (CASTEL). Some well known risk factors (left ventricular hypertrophy, glucose intolerance, cholesterol, ApoB/ApoA ratio, triglycerides, proteinuria, cigarette smoking, and ECG abnormalities), whose importance in cardiovascular risk is definitely accepted for young adults, were very poor predictors of mortality in our survey. On the contrary, FEV1 reduction and blood uric acid were strong predictors.

Age Factors↗