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Biomedical subjects

A Colombo

Publications and source records attributed to A Colombo.

At least 163 records · Page 9Linked to original sources
PubMed1999

Platelet glycoprotein IIb/IIIa antagonists in percutaneous coronary revascularization.

Coronary dissections and intracoronary thrombosis are the most important determinants of acute and subacute complications occurring during coronary interventions. Stents have proved efficacious to repair coronary dissections. The formation of intracoronary thrombi during percutaneous coronary intervention (PCI), the other main pathogenic mechanism for acute complications of PCI, has also been implicated in the pathogenesis of long-term ischemic outcomes. To reduce intracoronary thrombosis, all PCIs have been historically performed during intense short-term anticoagulation with the combination of unfractionated heparin plus aspirin. Compelling data on the central role of platelets in arterial thrombosis have made apparent the need for more potent antiplatelet agents for the treatment of patients undergoing PCI.

Abciximab↗
PubMed1999

The effects of a single intercuspal interference on electromyographic characteristics of human masticatory muscles during maximal voluntary teeth clenching.

In 13 healthy subjects (eight men and five women, mean age, 22 years), an aluminum intercuspal interference (height, 0.25 mm) was placed on the maxillary right first premolar to study its effect on the contractile symmetry of the right and left masseter and anterior temporalis muscles when measured through a Percentage Overlapping Coefficient (POC), derived from surface electromyographic recordings of maximum voluntary teeth clenching. Additionally, and to estimate the potential of the experimental intercuspal interference to induce lateral displacement of the mandible, a Torque Coefficient (TC) was derived from surface electromyographic recordings. The conclusion was that the experimental occlusal interference gave rise to asymmetric contractile activity in the studied mandibular elevator muscles as well as a potential to displace the mandible in a lateral direction.

Adult↗
PubMed1999

Supplementation of Jurkat T cells with green tea extract decreases oxidative damage due to iron treatment.

Regular tea consumption has been associated with a reduced risk of cancer. As demonstrated in vitro, green tea contains catechins with antioxidant properties. We evaluated the effect of the supplementation of the Jurkat T-cell line with green tea extract on oxidative damage. Cells grown in medium with or without green tea extract (10 mg/L) were treated with Fe(2+) (100 micromol/L) as an oxidative stimulus for 2 h. Cell membrane lipid peroxidation was evaluated by fatty acids pattern analysis and malondialdehyde production in alpha-linolenic acid-loaded cells. Furthermore, oxidative DNA damage (single strand breaks) was detected in cells by the Comet assay and quantified as relative tail moment (RTM). Supplementation with green tea extract significantly decreased malondialdehyde production (1.6 +/- 0.3 vs. 0.6 +/- 0.1 nmol/mg protein, P < 0.05) and DNA damage (0.32 +/- 0.07 vs. 0.12 +/- 0.04 RTM, P < 0.05) after Fe(2+) oxidative treatment. In control cells, there was no effect on membrane distribution of (n-3) fatty acids due to Fe(2+) treatment. Cell enrichment with alpha-linolenic acid increased total membrane (n-3) fatty acids. However, the oxidative treatment did not modify the distribution of polyunsaturated fatty acids. It is likely that the observed protective effects can be attributed to epigallocatechin gallate, which is present mainly (670 g/kg) in green tea extract; however, we cannot exclude contributions by other catechins. These data support a protective effect of green tea against oxidative damage.

DNA Damage↗
PubMed1999

Detection of rifampin resistance in Mycobacterium tuberculosis by double gradient-denaturing gradient gel electrophoresis.

We applied double gradient-denaturing gradient gel electrophoresis (DG-DGGE) for the rapid detection of rifampin (RMP) resistance from rpoB PCR products of Mycobacterium tuberculosis isolates and clinical samples. The results of this method were fully concordant with those of DNA sequencing and susceptibility testing analyses. DG-DGGE is a valid alternative to the other methods of detecting mutations for predicting RMP resistance.

Adult↗
PubMed1999

Multicenter evaluation of the XT modular coronary stent: clinical and angiographic results.

BACKGROUND: In the past few years, the indications for stent implantation have broadened, along with a larger number of available designs. The Bard XT stent is a new modular stent with an original structure and design. METHODS: To evaluate the new Bard XT stent, we studied its use in a multicenter experience in 163 patients, with a total of 168 lesions and 180 implanted units. RESULTS: Despite the predominance of complex lesions, the procedural success rate was 98%, with only a 2% failure of stent implantation. There was only one death (no-reflow phenomenon in a rescue primary PTCA in a patient in cardiogenic shock) without other major periprocedural complications. Centralized QCA showed a statistically significant increase of MLD (from 0.73 +/- 0.43 mm to 2.71 +/- 0.40 mm, p < 0.0001) and DS reduction (from 73.8 +/- 15.1% pre-treatment to 7.8 +/- 0.4% after stent implantation; p < 0.0001). Aspirin and ticlopidine were routinely administered after the procedure. Thirty-day follow-up reported only one case of subacute stent thrombosis (in the first day), treated with re-PTCA. CONCLUSIONS: In a group of patients with complex lesions, we obtained a high rate of success with a low incidence of complications. The Bard XT stent had a high-performance profile with normalization of vessel diameter and angiographic results similar to the ones obtained with the "slotted tube" stents.

Aged↗
PubMed1999

Simplified cephalometric lines for the estimation of muscular lines of action.

In the study of masticatory muscle performance, one of the biomechanical variables that can be estimated is the mechanical advantage of the masticatory muscles, namely, the ratio between the muscular moment arm and the bite force moment arm. In the present study, the position of the estimated line of action of the masseter muscle, drawn between gonion and orbitale (Go-Or) relative to dental (occlusal plane) and skeletal (Frankfort plane) references was analyzed in 431 pretreatment lateral cephalograms of orthodontic patients (195 males, 236 females) aged 6 to 50 years, and in the lateral tracings of the Bolton standards (6 to 18 years of age). The following measurements were evaluated: (1) skeletocutaneous class (soft tissue equivalent of Wits appraisal, linear distance in millimeters between the projections of points A' and B' on the occlusal plane); (2) angle between the Go-Or line and the perpendicular to the occlusal plane at the molar occlusal point; and (3) angle between the Go-Or line and the Frankfort plane. In the patients, the skeletocutaneous class ranged between--14.5 and 15.5 mm, without any sex- or age-related differences. The angle between the Go-Or line and the perpendicular to the occlusal plane was, on average, 39 degrees (range 15 to 53 degrees), and it decreased with advancing age; while the average angle between Go-Or and Frankfort plane was 42 degrees (range 30 to 54 degrees), and it increased in older patients. No effects of sex were found. The two angles were significantly correlated to each other, while no correlations were found with the sagittal jaw discrepancy. Similar results were obtained on the Bolton tracings. Overall, the present cephalometric analogue could be useful in biomechanical simulations.

Adolescent↗
PubMed1999

Use of N-acetylcysteine in the management of coronary artery diseases.

Thrombolysis after acute myocardial infarction may lead to a number of adverse effects (reperfusion injury) such as myocardial stunning, arrhythmias and even myocardial damage and extension of the infarct size. Some recent clinical studies have demonstrated that the intravenous infusion of N-acetylcysteine during thrombolysis was associated with a decrease in infarct size and better preservation of left ventricular function, probably due to antioxidant and free radical scavenger properties of N-acetylcysteine. Short- and long-term studies indicated that also in patients with unstable angina pectoris and threat of infarct, the intravenous or oral administration of N-acetylcysteine in association with nitroglycerin is highly effective in decreasing the risk of worsening, mainly by preventing the occurrence of acute myocardial infarction.

Acetylcysteine↗
PubMed1999

Endovascular treatment of aortic aneurysms of the abdominal aorta with covered stents.

Abdominal aortic aneurysms are common in the aging population; their surgical treatment is well established and allows good results in specialized centers. Endovascular exclusion of abdominal aortic aneurysms has been shown to be feasible since 1991 and nowadays commercially available bifurcated endografts allow safe exclusion in selected cases. In the last year 22 patients with an aorto-iliac aneurysm received endovascular treatment at our Institution. We included patients with favorable anatomic characteristics (i.e. neck > 15 mm length, and < 28 mm diameter, iliac neck < 12 mm diameter, absence of > 90 degrees iliac or aortic angulation) and, in particular, those with increased surgical risk for systemic pathology (12 patients), or hostile abdomen (9 patients). We employed Vanguard II (Boston Scientific) endovascular grafts introduced through a surgically exposed common femoral artery; the contralateral limb of bifurcated grafts was inserted percutaneously. The endograft was successfully implanted in all cases, requiring additional iliac cuffs for complete aneurysm exclusion in 3 cases. Periprocedural morbidity included one case of thrombosis and one case of pseudoaneurysm of the punctured femoral artery, which required surgical treatment. In one case surgical exposure of the iliac artery was required in order to advance the device into the aorta. In one patient who previously underwent hemicolectomy, postoperative colonic ischemia was observed, and pharmacological treatment was required. Moreover we also observed one case of groin infection that was treated successfully with local wound care and systemic antibiotics, and one late contralateral limb thrombosis that was successfully treated with loco-regional thrombolysis. The mean follow-up was 6.1 months: one patient died because of congestive heart failure. No further morbidity was recorded. A type-II endoleak was observed in one patient, originating from the inferior mesenteric artery with no sac enlargement; this patient is still under observation. In conclusion, with proper clinical selection, commercially available endovascular devices allow safe exclusion of abdominal aortic aneurysms. Long-term follow-up is needed to ascertain the durability of the procedure.

Aorta, Abdominal↗
PubMed1999

Dental arch size in healthy human permanent dentitions: ethnic differences as assessed by discriminant analysis.

Race and ethnicity variably influence the form of the human craniofacial complex. In the present study, the effects of ethnicity and sex on the global size of normal adult dental arches were analyzed. The dental arches of 47 northern Chilean mestizos (25 men, 22 women) and 95 northern Italian Caucasians (50 men, 45 women) were cast in stone. All subjects had a complete dentition in both arches. In all models the coordinates of dental cusp tips were digitized using an image analyzer. The center of gravity of each tooth was computed and arches were interpolated using a polynomial model (y = ax + bx2 + cx3 + dx4). In all arches, the intercanine, intermolar, and mid-intercanine to mid-intermolar distances were computed from the dental centers of gravity. These arch distances were entered in a linear discriminant function analysis. The polynomial model accurately interpolated data points in all instances, and most of the dental arch form was determined by the first and second degree coefficients. On average, Italian Caucasian arches were smaller than Chilean mestizo arches. Male mean distances were larger than female distances regardless of ethnic group or arch. The linear discriminant analysis performed between male and female arches within ethnic groups was significant only for both Italian Caucasian arches, but the percentage errors for the classification of a new individual were very high (about 30%). Conversely, Italian Caucasian arches could always be discriminated from Chilean mestizo arches of the same sex with a much smaller error.

Adult↗
PubMed1998

Angiographic and intravascular ultrasound predictors of in-stent restenosis.

OBJECTIVES: This study was performed to determine predictors of in-stent restenosis from a high volume, single-center practice. BACKGROUND: Intracoronary stents have been shown to reduce the restenosis rate as compared with balloon angioplasty, but in-stent restenosis continues to be an important clinical problem. METHODS: Between April 1993 and March 1997, 1,706 patients with 2,343 lesions were treated with a variety of intracoronary stents. The majority of stents were placed with high pressure balloon inflations and intravascular ultrasound (IVUS) guidance. Angiographic follow-up was obtained in 1,173 patients with 1,633 lesions (70%). Clinical, angiographic and IVUS variables were prospectively recorded and analyzed by univariate and multivariate models for the ability to predict the occurrence of in-stent restenosis defined as a diameter stenosis > or =50%. RESULTS: In-stent restenosis was angiographically documented in 282 patients with 409 lesions (25%). The restenosis group had a significantly longer total stent length, smaller reference lumen diameter, smaller final minimal lumen diameter (MLD) by angiography and smaller stent lumen cross-sectional area (CSA) by IVUS. In lesions where IVUS guidance was used, the restenosis rate was 24% as compared with 29% if IVUS was not used (p < 0.05). By multivariate logistic regression analysis, longer total stent length, smaller reference lumen diameter and smaller final MLD were strong predictors of in-stent restenosis. In lesions with IVUS guidance, IVUS stent lumen CSA was a better independent predictor than the angiographic measurements. CONCLUSIONS: Achieving an optimal stent lumen CSA by using IVUS guidance during the procedure and minimizing the total stent length may reduce in-stent restenosis.

Aged↗