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Biomedical subjects

M Berti

Publications and source records attributed to M Berti.

At least 73 records · Page 4Linked to original sources
PubMed1996

Straddling endoventricular pericardial patch in mitral valve repair with the sliding leaflet technique.

Calcification of the mitral annulus is always a technical complication in mitral surgery and standard procedures are often difficult to perform; mitral valve replacement can be dangerous with a high risk of perioperative heart rupture, and reconstructive surgery is often contraindicated. Nevertheless in this case of posterior leaflet prolapse with annular calcification valve repair was performed, after complete calcium debridement causing annulus disruption and atrio-ventricular discontinuity, by means of a straddling atrio-ventricular pericardial patch and the sliding leaflet technique.

Calcinosis↗
PubMed1995

Oligotide, a new single-stranded oligodeoxyribonucleotide, preserves postsynaptic beta-adrenergic and cholinergic receptor functions in rabbit hearts after acute infarction.

Acute myocardial infarction was induced in New Zealand male albino rabbits. 3 days after surgery, the mortality rate and plasma CPK activity were reduced by 64% and 66% respectively by intravenous infusion of Oligotide (32 mg/kg/h for 6h), a single-stranded oligodeoxyribonucleotide of mammalian origin. Perfused hearts, obtained from Oligotide-treated rabbits 3 days after surgery, showed a strength of contraction in the range of that of hearts of sham-operated animals and an ameliorated postsynaptic beta-adrenergic and cholinergic receptor function. In addition, in these hearts, "ex vivo" treatment with Oligotide resulted in almost complete preservation of both adrenergic and cholinergic responses to their specific agonists. These data suggest that Oligotide by protecting the hearts from the ischemic damage and possibly by restricting left ventricular tissue necrosis may have normalized the biological responses of this organ to isoproterenol and preserved the integrity of coronary endothelial-dependent relaxant function.

Acetylcholine↗
PubMed1995

Antimicrobial activity of MDL 63,246, a new semisynthetic glycopeptide antibiotic.

MDL 63,246 is a semisynthetic derivative of the naturally occurring glycopeptide antibiotic MDL 62,476 (A40926). It was more active in vitro against Staphylococcus aureus and coagulase-negative staphylococci than MDL 62,476, teicoplanin, and vancomycin and was more active than mideplanin (MDL 62,873) against some isolates. MDL 63,246 had excellent activity against streptococci and teicoplanin-susceptible enterococci, and it also had in vitro activity against some VanA enterococcal isolates. It was more active than teicoplanin and vancomycin against acute staphylococcal, streptococcal, and enterococcal septicemia in immunocompetent and neutropenic mice. It was highly efficacious in reducing the bacterial load in the hearts of rats in staphylococcal endocarditis experiments and the bacterial load of Staphylococcus epidermis in a high infection model in neutropenic mice. The excellent in vivo activity of MDL 63,246 appears to correlate both with its in vitro antibacterial activity and with its long half-life in rodents.

Animals↗
PubMed1994

Long-term use of K-strophanthin in advanced congestive heart failure due to dilated cardiomyopathy: a double-blind crossover evaluation versus digoxin.

K-strophanthin or digoxin were added to diuretics (all cases) and vasodilators (most cases) for treating advanced congestive heart failure in 22 patients with dilated cardiomyopathy and sinus rhythm. K-strophanthin (0.125 mg intravenously) or digoxin (0.25 mg orally) were administered daily in two 3-month periods, during which vasodilators and diuretics were kept constant and patients received one of the two digitalis preparations in a double-blind fashion, crossing over to the alternative preparation in the next period. Blindness was assured throughout the trial with a daily intravenous injection of 10 ml normal saline solution either containing K-strophanthin or not, and with daily oral administration of either placebo or active digoxin. At the end of the run-in period, 15 days after starting active preparations, and thereafter every month for the next 6 months, we evaluated left ventricular pump function at rest and patients' functional performance by a cardiopulmonary exercise test. At Day 15, cardiac index and ejection fraction at rest, compared with run-in, were significantly raised with both glycosides; during exercise while on K-strophanthin, peak oxygen consumption was augmented by 1.4 ml/min/kg (p < 0.01) and oxygen consumption at anaerobic threshold by 2.2 ml/min/kg (p < 0.01); corresponding variations on digoxin (-0.1 and +0.3, respectively) were not significant versus run-in. These patterns were duplicated at repeated tests during follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Facilitation of coronary spasm by propranolol in Prinzmetal's angina: fact or unproven extrapolation?

BACKGROUND: Alpha-adrenergic activation enhances coronary vascular tone; beta-blockade leaves alpha-adrenergic vasoconstriction unopposed. Whether beta-adrenergic blockade facilitates coronary spasm in patients with Prinzmetal's angina is unknown. METHODS: Using quantitative angiography, we evaluated the response of normal and narrowed coronary arteries to intravenous propranolol, a cold pressor test (an alpha-stimulus), and the combination of the two in 15 patients with Prinzmetal's (group 1) and in 19 with classic (group 2) angina. From measurements of heart rate, systemic and pulmonary arterial pressures, and left and right ventricular ejection times, we derived the tension-time index per minute as a measure of the oxygen need (O2 demand) of the whole heart. RESULTS: In group 1, cold invariably constricted normal and diseased vessels, and in two patients elicited spasm at sites of significant lesions; these changes did not correlate with those in O2 demand. In group 2, the vasomotor reaction of normal and narrowed vessels in response to cold correlated with the modifications in O2 demand. After propranolol administration, (1) in normal vessels in both groups, the baseline luminal diameter varied in parallel with the changes in myocardial O2 demand; (2) narrowings in group 1 patients invariably dilated and in group 2 the caliber varied according to changes in O2 demand; (3) during cold stimulation, luminal narrowing in group 1 varied in parallel with O2 demand, and, in group 2, vessels were uniformly constricted. CONCLUSION: These results do not support the facilitation of coronary spasm by propranolol in Prinzmetal's angina and support the hypothesis that the contractility of coronary vessels in patients with this form of angina is different from that in the classic form.

Adult↗
PubMed1994

Pericardial effusion after cardiac surgery: incidence, site, size, and haemodynamic consequences.

OBJECTIVE: To evaluate the incidence, characteristics, and haemodynamic consequences of pericardial effusion after cardiac surgery. DESIGN: Clinical, echocardiographic, and Doppler evaluations before and 8 days after cardiac surgery; with echocardiographic and Doppler follow up of patients with moderate or large pericardial effusion after operation. SETTING: Patients undergoing cardiac surgery at a tertiary centre. PATIENTS: 803 consecutive patients who had coronary artery bypass grafting (430), valve replacement (330), and other types of surgery (43). 23 were excluded because of early reoperation. MAIN OUTCOME MEASURES: Size and site of pericardial effusion evaluated by cross sectional echocardiography and signs of cardiac tamponade detected by ultrasound (right atrial and ventricular diastolic collapse, left ventricular diastolic collapse, distension of the inferior vena cava), and Doppler echocardiography (inspiratory decrease of aortic and mitral flow velocities). RESULTS: Pericardial effusion was detected in 498 (64%) of 780 patients and was more often associated with coronary artery bypass grafting than with valve replacement or other types of surgery; it was small in 68.4%, moderate in 29.8%, and large in 1.6%. Loculated effusions (57.8%) were more frequent than diffuse ones (42.2%). The size and site of effusion were related to the type of surgery. None of the small pericardial effusions increased in size; the amount of fluid decreased within a month in most patients with moderate effusion and in a few (7 patients) developed into a large effusion and cardiac tamponade. 15 individuals (1.9%) had cardiac tamponade; this event was significantly more common after valve replacement (12 patients) than after coronary artery bypass grafting (2 patients) or other types of surgery (1 patient after pulmonary embolectomy). In patients with cardiac tamponade aortic and mitral flow velocities invariably decreased during inspiration; the echocardiographic signs were less reliable. CONCLUSIONS: Pericardial effusion after cardiac surgery is common and its size and site are related to the type of surgery. Cardiac tamponade is rare and is more common in patients receiving oral anticoagulants. Echo-Doppler imaging is useful for the evaluation of pericardial fluid accumulations after cardiac surgery. It can identify effusions that herald cardiac tamponade.

Adolescent↗
PubMed1994

[Multiplane transesophageal echocardiography for the monitoring of cardiac surgery].

Multiplane transesophageal echocardiography (TEE) allows visualization of the heart and great vessels through an infinite number of imaging planes and improves the diagnostic capabilities of mono and biplane TEE. This study was undertaken to test whether MTEE is a useful intraoperative monitoring method during cardiac surgery. Intraoperative multiplane TEE was performed in 200 patients (mean age 56 +/- 19 years) as a part of the routine clinical care. We systematically acquired cardiac images from the gastric fundus (short and long axes of the ventricles), lower esophagus (four-chamber, two-chamber, and long axis), upper esophagus (13 views concerning the aorta, pulmonary artery, left and right atrium, systemic and pulmonary veins, coronary arteries, right ventricular outflow tract), and searched for complete views of the thoracic descending aorta. All views analyzed in the preoperative (immediately before cardiopulmonary bypass), intraoperative and postoperative phases evaluating: the angle between current and 0 degree at which each view was obtained; the success rate of each view; the usefulness of the different views in providing essential additional clinical information compared to 0 degrees and 90 degrees of the traditional biplane TEE. Most views of the heart and great vessels were visualized in oblique planes, and other views were significantly improved thanks to slight angle corrections. Multiplane TEE was particularly useful in the preoperative and postoperative phases of aortic dissection (11 cases), mitral valve repair (13 cases), left ventricular aneurysmectomy (9 cases), right atrial thrombosis (1 case), positioning of left ventricular hemopump (2 cases), mitral-aortic endocarditis (3 cases), bleeding from proximal suture of an aortic heterograft (1 case).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Efficacy of a central venous catheter (Hydrocath) loaded with teicoplanin in preventing subcutaneous staphylococcal infection in the mouse.

Segments (1 cm in length) of a central venous catheter (Hydrocath) coated with teicoplanin, or uncoated, were inserted subcutaneously into mice and Staphylococcus aureus or Staphylococcus epidermidis were inoculated nearby. At 24 and 48 h after infection, the mean titre of adherent bacteria (recovered by sonication) for the teicoplanin-coated catheters was less than 10 CFU as compared to more than 10(4) CFU (S. aureus) and 10(3) CFU (S. epidermidis) from the uncoated catheters. In the S. aureus infection, teicoplanin coating also prevented the formation of abscesses which were observed around uncoated catheters.

Animals↗
PubMed1993

Nitric oxide and prostacyclin influence coronary vasomotor tone in perfused rabbit heart and modulate endothelin-1 activity.

Using isolated perfused rabbit heart electrically paced, we assessed the relevance of both nitric oxide (NO) and prostacyclin (PGI2) in regulation of resting coronary perfusion pressure (CPP). In preparations in which NO-synthase was inhibited by NG-monomethyl-L-arginine (L-NMMA, 10 microM), resting CPP increased significantly; this phenomenon was potentiated by indomethacin infusion (3 microM), prevented by L-arginine (100 microM) and significantly reduced by iloprost (55 nM) and defibrotide (200 micrograms/ml). Furthermore, the increase in resting CPP induced by graded doses of endothelin-1 (ET-1 0.6-160 pmol), was further augmented by blocking of prostaglandin biosynthesis with indomethacin (3 microM) and was substantially reduced when the rate of formation of PGI2 was enhanced by defibrotide (200 micrograms/ml). Moreover, the coronary vasoconstriction induced by ET-1 (2, 4, and 8 pmol) was increased in hearts in which NO-synthase was blocked by L-NMMA (10 microM) and this event was abolished in preparations in which PGI2 synthesis was stimulated by defibrotide (200 micrograms/ml). These results further emphasize that rabbit coronary vessels are continuously dilated by NO released from endothelial cells. They also indicate that PGI2 takes part in NO generation in the endothelial-derived relaxing mechanism. Inactivation of this mechanism, owing to decreased formation of NO and PGI2 in rabbit heart, induces hyperreactivity of coronary smooth muscles to ET-1. Finally, an increase in PGI2 production (such as that caused by defibrotide) may counterbalance impaired NO generation and attenuate hyperreactivity of the coronary vasculature.

Animals↗
PubMed1993

In vitro antimicrobial activity of a new antibiotic, MDL 62,879 (GE2270 A).

MDL 62,879 (GE2270 A) is a new peptide antibiotic that inhibits protein synthesis through an interaction with elongation factor Tu. MDL 62,879 was very active against gram-positive clinical isolates, particularly staphylococci and enterococci, for which MICs for 90% of isolates were < or = 0.13 micrograms/ml. It was equally active against isolates resistant to beta-lactams, erythromycin, gentamicin, and glycopeptides. It also had activity against Mycobacterium tuberculosis. MDL 62,879 had moderate bactericidal activity against staphylococci.

Anti-Bacterial Agents↗
PubMed1993

N63-carboxamides of N15-alkyl and N15,N15-dialkyl derivatives of teicoplanin and deglucoteicoplanin.

The synthesis and biological properties of a series of N63-carboxamides of 15-N-alkylated derivatives of teicoplanin A2 (CTA) and its aglycone (TD) are described. Among the compounds, those carrying hydrophilic groups or ionizable amino functions on the N15-alkyl chain are more soluble in water than parent N15-methylated or unmodified amides. Selected compounds were more active in vitro than CTA or TD, and a few of them were also slightly more efficacious in vivo than the parent antibiotics in streptococcal septicemia in the mouse. Their degree of activity varied with the structure and length of the N15-alkyl chains.

Alkylation↗
PubMed1993

[The improvement of the Doppler echocardiographic method for the estimation of pulmonary systolic pressure].

The formulas currently utilized for noninvasive evaluation of right ventricular systolic pressure (RVSP) include right ventricular-right atrial pressure gradient (RV-RAG) and right atrial pressure (RAP). The former is expressed by trans-tricuspid systolic flow velocity, the latter is generally assumed. We recently observed that ultrasound estimation of RAP through inferior vena cava collapsibility index (CI) may help in the choice of the more appropriate formula for the evaluation of RVSP. However, these traditional methods (method A:RV-RAG + 10; method B:RV-RAG x 1.1 + 14) have limitations, particularly when RAP is low. The present study was undertaken to improve noninvasive estimation of RVSP through new formulas based on CI prediction of RAP. One hundred and four patients, in whom tricuspid regurgitation was adequately documented with CW-Doppler, were included in this study. They were classified into 3 groups: Group 1 with CI > 45%, Group 2 with CI < or = 35%, Group 3 with CI 35-45%. RVSP was evaluated by 3 different methods: A, B, and C. Method C was based on CI, assigning 6, 16, or 9 mmHg to RAP (respectively, the mean values in the 3 groups of our previous study). Results indicate that method C improves noninvasive estimation of RVSP in Group 1 and Group 2, with respect to other methods, with reduction of the SEE and of the mean difference of the t-test between hemodynamic and echographic values. In Group 3, Doppler estimation by method A and C, and catheter measurements are comparable, whereas method B significantly overestimates the actual value.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Autoradiographic detection of vasopressin binding sites, but not of oxytocin binding sites, in the sheep olfactory bulb.

Oxytocin facilitates maternal behaviour in sheep. In the present study, we searched for the presence of oxytocin and vasopressin binding sites in the sheep olfactory bulb, a brain area which is thought to be involved in specific bond formation between the ewe and its lamb. Using in vitro autoradiography, we observed binding of tritiated vasopressin to the glomerular layer of the olfactory bulb. Competition studies performed with structural analogues and the use of a 125I-labelled linear vasopressin antagonist suggested that sites which bind vasopressin are V1 type receptors. In contrast, specific binding sites for oxytocin in the olfactory bulb could be detected neither in control females, nor in ovariectomized females treated with estradiol nor in postparturient ewes, although such sites were present in the uterus.

Animals↗
PubMed1992

Synthesis and antibacterial activity of a series of basic amides of teicoplanin and deglucoteicoplanin with polyamines.

Basic carboxamides of teicoplanin A2 (CTA) and its aglycon (TD) are prepared by condensation of the 63-carboxyl function of these antibiotics with linear or branched polyamines. The antimicrobial activities of some of the resulting compounds were better than those of the unmodified antibiotics. The presence of more than one basic group in the amidic chain enhanced the in vitro activity of some TD-amides against Gram-negative bacteria; two of these derivatives were also effective in vivo against Escherichia coli septicemia in the mouse. Among the CTA derivatives, the amide with spermine showed some unexpected in vitro activity against Gram-negatives. Both CTA- and TD-amides with polyamines are very soluble in water over a wide range of pH and are very hydrophilic.

Amides↗
PubMed1992

Antimicrobial activity of MDL 62,873, a semisynthetic derivative of teicoplanin, in vitro and in experimental infections.

MDL 62,873 is an amide derivative of teicoplanin A2-2. Like those of natural glycopeptides, its antibacterial activity is mediated by inhibition of cell wall peptidoglycan synthesis. Against streptococci and enterococci, the in vitro activity of MDL 62,873 was similar to that of teicoplanin and greater than that of vancomycin. Against staphylococci, it has activity similar to that of vancomycin, and it was significantly more active than teicoplanin against coagulase-negative isolates. Like teicoplanin and vancomycin, MDL 62,873 had slow but significant bactericidal activity (99 to 99.9% killing in 24 h) against staphylococci at concentrations near the MIC. In murine septicemia studies with Staphylococcus aureus, Streptococcus pyogenes, and Streptococcus pneumoniae, the 50% effective doses were lower than those of vancomycin. In staphylococcal endocarditis in rats, MDL 62,873 at 20 mg/kg of body weight and vancomycin at 40 mg/kg, both doses given intravenously twice daily, had similar efficacies in reducing the heart bacterial load. These results probably reflect the longer half-life of MDL 62,873, which has a pharmacokinetic profile in rats similar to that of teicoplanin.

Animals↗
PubMed1992

Exercise performance in patients with uncomplicated essential hypertension. Effects of nifedipine-induced acute blood pressure reduction.

In untreated patients with uncomplicated essential hypertension, exercise induces an abnormal increase in blood pressure; the influences of this increase on exercise were evaluated by a cardiopulmonary exercise test (CPX) performed in control conditions (step 1) and during acute blood pressure reduction (step 2). Patients were classified as (1) normotensive (resting diastolic blood pressure [BPd] less than 90 mm Hg; n = 14), (2) mildly hypertensive (BPd of 90 to 104 mm Hg; n = 9), and (3) moderately to severely hypertensive (BPd greater than or equal to 105 mm Hg; n = 16). For the three groups, peak mean blood pressure during exercise was 125 +/- 5 mm Hg (mean +/- SEM), 144 +/- 3 mm Hg (p less than 0.01 vs normotensive), and 161 +/- 4 mm Hg (p less than 0.01 vs normotensive and p less than 0.01 vs mild hypertension), respectively. Oxygen consumption (VO2) at peak exercise and at ventilatory anaerobic threshold was 26.1 +/- 1.1 and 17.2 +/- 0.5 ml/min/kg, 25.4 +/- 1.1 and 16.9 +/- 0.8 ml/min/kg, and 26.4 +/- 1.3 and 17.5 +/- 1.2 ml/min/kg in normotensive subjects, those with mild hypertension, and those with moderate to severe hypertension, respectively. Fourteen normotensive subjects, six with mild hypertension, and nine with moderate to severe hypertension participated to step 2 (nifedipine vs placebo, double-blind crossover). Nifedipine reduced blood pressure at rest and at peak exercise in those with hypertension. Peak exercise VO2 was unaffected by nifedipine in both normotensive subjects and those with hypertension. With nifedipine, ventilatory anaerobic threshold occurred earlier and at a lower VO2 in mild and in moderate to severe hypertension (delta VO2 = -1.9 and -2.4 ml/min/kg, respectively). These findings might be due to nifedipine-induced redistribution of blood flow during exercise and might be the reason for the complaint of weakness after blood pressure reduction in hypertensive subjects.

Blood Pressure↗
PubMed1992

[Better efficacy of K-strophanthidin versus digoxin in subjects with dilated cardiomyopathy and chronic heart insufficiency].

We evaluated the efficacy of K-strophanthidin and digoxin in 20 patients with stable, severe congestive heart failure. In this aim, we studied the left ventricular pump function at rest and following manipulation of the cardiac load (cold pressor test and nitroprusside infusion), the exercise performance (cardiopulmonary exercise test), and the level of circulating norepinephrine. The study was double-blind and cross-over and comprehended 4 periods of 1-week each during which patients received in random order: placebo (oral+intravenous), K-strophanthidin (intravenous + oral placebo), digoxin (oral+intravenous placebo and, in 8 patients, intravenous + oral placebo). The efficacy of the various compounds was tested at the end of each period 1 and 10 hours after drug dosing. Comparable results were obtained by the 2 sets of measurements. Both digoxin and K-strophanthidin showed a positive inotropic effect. This is shown by an upward shift of the ejection fraction/end-systolic stress. In spite of this, only K-strophanthidin significantly increased exercise performance: tolerance time (+153 s), peak oxygen consumption (+1.2 ml/kg/min) and oxygen consumption at anaerobic threshold (+2.3 ml/kg/min). Norepinephrine plasma level at rest was significantly lowered only by K-strophanthidin. Results were comparable when digoxin was given intravenously. We conclude that both glycosides elicit an increase of the inotropic cardiac state but only K-strophanthidin improves exercise performance.

Administration, Oral↗