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Biomedical subjects

A Colombo

Publications and source records attributed to A Colombo.

At least 127 records · Page 7Linked to original sources
PubMed1999

Effectiveness of clopidogrel and aspirin versus ticlopidine and aspirin in preventing stent thrombosis after coronary stent implantation.

BACKGROUND: Ticlopidine has been shown to reduce the incidence of stent thrombosis compared with warfarin, but it may cause serious hematological side effects. Clopidogrel, a new thienopyridine derivative, may be a safe alternative to ticlopidine. The aim of this study was to compare the safety and efficacy of clopidogrel and aspirin with those of ticlopidine and aspirin in patients undergoing coronary stent implantation. METHODS AND RESULTS: The population of this study consisted of 2 groups: patients who underwent coronary stenting and were treated with ticlopidine and aspirin (TA group, n=1406), and patients who underwent coronary stenting followed by treatment with clopidogrel and aspirin (CA group, n=283). At 1-month follow-up, there was no difference in stent thrombosis (1.5% versus 1.4%, P=1.0) or major adverse cardiac events (3.1% versus 2.4%, P=0. 85) between the TA and CA groups, respectively. The probability of any side effect (neutropenia, diarrhea, rash) was significantly higher in the TA group (10.6% versus 5.3%, P=0.006; relative risk, 0. 53; CI, 0.32 to 0.86). CONCLUSIONS: These data suggest that clopidogrel may be an effective pharmacological regimen after coronary stent implantation. Furthermore, the simpler dosing regimen, the absence of neutropenia, and the lower frequency of other side effects make it a safe alternative to ticlopidine.

Aged↗
PubMed1999

Does the specific intravascular ultrasound criterion used to optimize stent expansion have an impact on the probability of stent restenosis?

Intravascular ultrasound (IVUS) imaging has been used to optimize stent implantation in coronary arteries, but the criteria used were chosen on an empiric basis. The aim of this study was to determine whether any of these criteria have an independent role in predicting the probability of freedom from restenosis. The study population consisted of 425 patients (496 lesions) who underwent angiographically successful IVUS-guided stenting. Five IVUS criteria were studied: (1) intrastent minimal lumen cross-sectional area (ISMLCSA) > or =9 mm2; (2) ISMLCSA (> or =9 mm2 and > or =80% of average reference lumen cross-sectional area [CSA]); (3) ISMLCSA > or =90% of average reference lumen CSA; (4) ISMLCSA > or =90% of distal reference lumen CSA; and (5) ISMLCSA > or =55% of average reference vessel CSA. These criteria were met in 33%, 29%, 68%, 82%, and 69% of lesions, respectively. Angiographic follow-up was performed in 335 of 421 eligible patients (80%) at 5.3 +/- 2.7 months. An absolute ISMLCSA > or =9 mm2 was associated with the lowest restenosis, but this criterion was primarily achieved in large vessels. The only criterion that was associated with higher probability of freedom from restenosis independently from vessel size was an ISMLCSA > or =55% of average reference vessel CSA. Therefore, when IVUS is used to guide stent implantation an effort should be made to achieve the largest lumen safely possible. An ISMLCSA > or =55% of the average reference vessel CSA seems to be the most appropriate criterion in terms of frequency of achievement and in terms of increasing the probability of freedom from restenosis.

Coronary Angiography↗
PubMed1999

Granulocyte and natural killer activity in the elderly.

The deterioration of the immune system in ageing, 'immunosenescence', is thought to contribute to increased morbidity and mortality from infections and possibly autoimmune diseases and cancer. The most profound changes involve effector and immunoregulatory T-cell functions. Immunosenescence appears also to be related to changes in non specific immunity as well. In the present study we have assessed superoxide production, chemotaxis and the expression of the apoptosis-related molecule APO1/Fas (CD95) on neutrophils (PMN) from young and old subjects. Furthermore, we have measured the basal natural killer (NK) activity of young and elderly subjects and we have compared the number of CD16+ cells found in these two groups. We observed a significant decrease age-related both of formation of O2- and chemotaxis whereas no significant correlation between age and the expression of CD95 on granulocyte membrane was demonstrated, suggesting that an increase age-related of CD95-linked apoptosis of PMN should be not an important determinant in the decreased PMN function. We also observed a significant correlation between age and NK activity. The decreased NK cell function was not due to a decreased number of NK cells in effector cell preparations since the number of CD16+ cells was significantly increased in old subjects. In conclusion, our results show that in the elderly there is also a deficit of the aspecific immunity that might play a role in the pathogenic mechanisms of the immunosenescence.

Adult↗
PubMed1999

In-stent neointimal proliferation correlates with the amount of residual plaque burden outside the stent: an intravascular ultrasound study.

BACKGROUND: The aim of this study was to evaluate the relationship between residual plaque burden after coronary stent implantation and the development of late in-stent neointimal proliferation. METHODS AND RESULTS: Between January 1996 and May 1997, 50 patients underwent intravascular ultrasound (IVUS) interrogation at 6+/-1.2 months after coronary stent implantation in native coronary arteries. IVUS images were acquired with a motorized pullback, and cross-sectional measurements were performed within the stents at 1-mm intervals. The following measurements were obtained: (1) lumen area (LA), (2) stent area (SA), (3) area delimited by the external elastic membrane (EEMA), (4) percent neointimal area calculated as (SA-LA/SA)x100, and (5) percent residual plaque area calculated as (EEMA-SA)/EEMAx100. Volume measurements within the stented segments were calculated by applying Simpson's rule. In the pooled data analysis of 876 cross sections, linear regression showed a significant positive correlation between percent residual plaque area and percent neointimal area (r=0.50, y= 45.03+0.29x, P<0.01). There was significant incremental increase in mean percent neointimal area for stepwise increase in percent residual plaque area. Mean percent neointimal area was 16.3+/-10.3% for lesions with a percent residual plaque area of <50% and 27.7+/-11% for lesions with a percent residual plaque area of >/=50% (P<0.001). The volumetric analysis showed that the percent residual plaque volume was significantly greater in restenotic lesions compared with nonrestenotic lesions (58.7+/-4.3% versus 51.4+/-5.7%, respectively; P<0.01). CONCLUSIONS: Late in-stent neointimal proliferation has a direct correlation with the amount of residual plaque burden after coronary stent implantation, supporting the hypothesis that plaque removal before stent implantation may reduce restenosis.

Aged↗
PubMed1999

Interleukin-5 production by mononuclear cells from aged individuals: implication for autoimmunity.

It is well known that in the elderly a deterioration of immune functions may occur. Particularly, stimulation of T cells from aged individuals leads to different kind and/or size of responses if compared with the responses obtained from T cells from young individuals. At the same time, an increase in prevalence of autoantibodies occurs in elderly. The altered production of certain cytokines might explain this paradox of decreased responsiveness to foreign antigens in the face of an increased response to self-antigens. We and others have suggested that this kind of immune response might depend on an age-associated impairment of Th-1 type function that selectively affects production of cytokines involved in the control of cellular responses. In contrast, Th-2 type function is seemingly not affected in elderly, as suggested by normal in vitro production of cytokines involved in humoral responses. To strengthen this hypothesis, in this study we have analysed the influence of age on the ability of mitogen-stimulated cultures of peripheral blood mononuclear cells from human beings to produce another Th-2 type cytokine, i.e. interleukin-5 (IL-5). IL-5 content of both 24- and 48-h stimulated cultures from old individuals was greater than that of young ones, although this difference attained significance only at 48 h. We suggest that the decreased production of Th-1 type cytokines in the presence of a normal or even increased production of Th-2 type cytokines might account for the pattern of immune response which may be observed in elderly, i.e. a normal or increased humoral response, including an autoimmune one, in the face of a low cell mediated immune response.

Adult↗
PubMed1999

Size and shape of the human first permanent molar: a Fourier analysis of the occlusal and equatorial outlines.

Form can be viewed as a combination of size and shape. Shape refers to the boundary outline independently from its orientation, relation to reference planes, and dimension (or size). Shape and its changes could be quantified by mathematical methods such as the Fourier series. In this investigation, Fourier analysis has been used to quantify the morphologic characteristics (size and shape) of the outline of the occlusal surface and maximum circumference (equator) in 259 normal, healthy human first permanent maxillary and mandibular molars and to assess the effect of sex. Large within-group variability was found in the Fourier coefficients. Both equatorial and occlusal molar areas were on average larger in male than in female homologous teeth, but the difference was statistically significant only for the equatorial areas. The mean ratios between equatorial and occlusal dental areas were independent from arch (maxillary and mandibular), side, or sex. Both equatorial and occlusal outlines of left and right homologous molars within sex and arch were similar, without size and shape differences. Similarly, no sex differences in shape were found in the comparison of homologous teeth. The method used in the present study could supply information about dental shape in both its entirety and local variations. In particular, the method is extremely sensitive to local variations in dental shape, and it could be usefully employed to compare single teeth to a standard.

Adolescent↗
PubMed1999

Stent thrombosis: incidence and related factors in the R.I.S.E. Registry(Registro Impianto Stent Endocoronarico)

Although stent thrombosis has been greatly reduced by adequate stent expansion with high-pressure balloon inflations and by the use of antiplatelet drugs, this event is still frightening, as it may lead to acute myocardial ischemia resulting in acute myocardial infarction or sudden death. Therefore, the definition of factors associated with stent thrombosis may provide a better understanding of the mechanisms underlying this phenomenon and may permit us to define therapeutic strategies to further reduce its occurrence. The purpose of this study was to assess factors responsible for the occurrence of stent thrombosis after coronary stent implantation in 939 consecutive patients enrolled in the Registro Impianto Stent Endocoronarico (R.I.S.E. Study Group). Consecutive patients undergoing coronary stent implantation at 16 medical centers in Italy were prospectively enrolled in the registry. Clinical data, and qualitative and quantitative angiographic findings were obtained from data collected in case report forms at each investigator site. The study group consisted of 781 men and 158 women with a mean age of 59 yr: 1,392 stents were implanted in 1,006 lesions and expanded at a maximal inflation pressure of 14.7 +/- 3 atm. The great majority of patients (92%) received only antiplatelet drugs after coronary stenting. During hospitalization there were 45 major ischemic complications in 39 patients (4.2%): 13 events were related to acute or subacute thrombosis (1.4%). Another stent thrombotic event occurred in the first month of follow-up. On multivariate logistic regression analysis, stent thrombosis was related to the following factors: unplanned stenting (OR 3.46, 95% CI 1.65-7.23), unstable angina (OR 3.37, 95% CI 1.11-10.14) and maximal inflation pressure (OR 0.83, 95% CI 0.75-0.93). In conclusion, this registry shows that in an unselected population of patients undergoing coronary stenting, stent thrombosis occurs in less than 2% of patients and is significantly related to unplanned stent implantation, unstable angina, and maximal inflation pressure. The incidence of this phenomenon is likely to be further reduced by the use of new potent antiplatelet drugs, such as platelet glycoprotein IIb/IIIa antagonists.

Adult↗
PubMed1999

Lower restenosis rate with stenting following aggressive versus less aggressive rotational atherectomy.

The present study evaluated the acute and follow-up results of stenting following aggressive rotational atherectomy compared with stenting following less aggressive rotational atherectomy. Recent work has demonstrated that stenting following rotational atherectomy is a promising strategy for complex and calcified lesions. However, there is little information available regarding the optimal procedural technique of rotational atherectomy to be employed before stent implantation. Between May 1995 and February 1997, 162 lesions in 126 patients were stented following rotational atherectomy because of the presence of severe calcification on fluoroscopy or intravascular ultrasound (95%). The lesions were divided as to whether aggressive rotational atherectomy was performed or not. Aggressive rotational atherectomy, defined as the use of a final burr size > or =2.25 mm and/or final burr/vessel ratio > or =0.8, was performed in 56 lesions. A less aggressive rotational atherectomy strategy was performed in 106 lesions. Procedural Q-wave (8.9% vs. 1.9%, P<0.05) and non-Q-wave (11% vs. 1.9%, P<0.05) myocardial infarctions were observed more frequently after aggressive rotational atherectomy; there was no significant difference in the incidence of other procedural complications. Although there was no significant difference in minimal lumen diameter after the procedure (3.11+/-0.68 vs. 2.99+/-0.48 mm, NS), at follow-up a greater minimal lumen diameter was observed in the lesions treated with aggressive rotational atherectomy compared to those treated with less aggressive rotational atherectomy (2.12+/-1.31 vs. 1.56+/-0.89 mm, P<0.01). Restenosis rates were 50.0% in the lesions treated without aggressive rotational atherectomy and 30.9% in those treated with aggressive rotational atherectomy (P<0.05). There was no significant difference in the incidence of restenosis with a focal pattern between the two groups (25.0% vs. 21.4%, NS). In contrast, restenosis with a diffuse pattern was lower in lesions treated with aggressive rotational atherectomy than in those without aggressive rotational atherectomy (9.5% vs. 25.0%, P<0.05). Aggressive rotational atherectomy followed by stenting is a promising strategy to reduce the restenosis rate in calcified lesions. However, the aggressive strategy is associated with an increased risk of procedural myocardial infarction.

Calcinosis↗
PubMed1999

Treatment of a coronary aneurysm with a new polytetrafluoethylene-coated stent: a case report.

A 43-year-old man underwent implantation of a PTFE-covered stent to exclude an aneurysm in an aorto-coronary venous bypass graft. A successful aneurysm closure was achieved after high-pressure stent expansion and no intimal hyperplasia was observed within the PTFE-covered stent segment in the angiogram performed 9 months later. The technical characteristics and indications of this new coronary prosthesis are discussed based on the authors' recent experience in 63 patients.

Adult↗
PubMed1999

Focal wall overstretching after high-pressure coronary stent implantation does not influence restenosis.

To determine if vessel wall overstretching during coronary stenting is associated with a higher restenosis rate, the intravascular ultrasound morphological evaluation was performed following ultrasound criteria. A total of 468 lesions with successful coronary Palmaz-Schatz stenting guided by intravascular ultrasound were classified into the no overstretching group (n = 295) and the overstretching group (n = 147). There were 26 lesions not classifiable due to the poststent morphology. Balloon-to-vessel ratio was 1.12 +/- 0.17 in the no focal overstretching group and 1. 20 +/- 0.20 in the overstretching group (P < 0.0002). Follow-up angiogram was performed in 77% of no focal overstretching group and in 75% of the focal overstretching group. The restenosis rate of the no focal overstretching group was 19.8% and 20.9% in the focal overstretching group, respectively (P = 0.65). Focal overstretching was more frequent following balloon oversizing. No increase in restenosis rate, found in focal overstretched stented lesions, leads us to the hypothesis of a regulation of smooth-muscle-cell proliferation activated by the normalization of blood flow and of shear stress, when stent implantation succeeds in optimally improving the lumen. Cathet. Cardiovasc. Intervent. 48:24-30, 1999.

Coronary Angiography↗
PubMed1999

Successful treatment of a bifurcation lesion with the Carina Bard stent: A case report.

In the last years new techniques and user-friendly stents have improved the results of stent implantation in coronary bifurcational lesions but difficulties in stent deployment and incomplete coverage of the bifurcation remain a problem. We describe the case of a proximal lesion of the anterior descending artery involving a large diagonal branch treated with the Carina Bard bifurcate stent, a new device that allows the complete immediate coverage of a bifurcational lesion with a single stent. Cathet. Cardiovasc. Intervent. 48:89-92, 1999.

Coronary Angiography↗
PubMed1999

Isolation and cloning of multipotential stem cells from the embryonic human CNS and establishment of transplantable human neural stem cell lines by epigenetic stimulation.

Stem cells that can give rise to neurons, astroglia, and oligodendroglia have been found in the developing and adult central nervous system (CNS) of rodents. Yet, their existence within the human brain has not been documented, and the isolation and characterization of multipotent embryonic human neural stem cells have proven difficult to accomplish. We show that the developing human CNS embodies multipotent precursors that differ from their murine counterpart in that they require simultaneous, synergistic stimulation by both epidermal and fibroblast growth factor-2 to exhibit critical stem cell characteristics. Clonal analysis demonstrates that human C NS stem cells are multipotent and differentiate spontaneously into neurons, astrocytes, and oligodendrocytes when growth factors are removed. Subcloning and population analysis show their extensive self-renewal capacity and functional stability, their ability to maintain a steady growth profile, their multipotency, and a constant potential for neuronal differentiation for more than 2 years. The neurons generated by human stem cells over this period of time are electrophysiologically active. These cells are also cryopreservable. Finally, we demonstrate that the neuronal and glial progeny of long-term cultured human CNS stem cells can effectively survive transplantation into the lesioned striatum of adult rats. Tumor formation is not observed, even in immunodeficient hosts. Hence, as a consequence of their inherent biology, human CNS stem cells can establish stable, transplantable cell lines by epigenetic stimulation. These lines represent a renewable source of neurons and glia and may significantly facilitate research on human neurogenesis and the development of clinical neural transplantation.

Animals↗
PubMed1999

The ARTS study (Arterial Revascularization Therapies Study).

The rising costs of health care have forced policy makers to make choices, and new treatments are increasingly assessed in terms of the balance between additional costs and additional effects. The recent recognition that stenting has a major and long-lasting effect enhancing balloon PTCA procedure has made it imperative to compare in patients with multivessel disease the standard surgical procedure with multiple stenting in a large scale multinational and multicentre approach (19 countries, 68 sites). Selection and inclusion of patients is based on a consensus of the cardiac surgeon and interventional cardiologist on equal 'treatability' of patients by both techniques with analysis of clinical follow-up (event-free survival) on the short (30 day), medium (1 year), and long-term (3 and 5 year) with analysis of cost-effectiveness and quality of life (EuroQol and SF-36). Of the entire trial, the primary null hypothesis which needs to be rejected is that there will be no difference in event-free survival or effectiveness (E), at 1 year and also that the direct and indirect costs (C) per event-free year are not different between surgery or stenting. For this to become significant with a power of 90% one needs 1200 patients. Between April 97 and June 98, 1205 patients have been randomized with a monthly recruitment of 83 patients. Expected costs, effects and cost-effectiveness ratio (CE ratio) are: Stent high costs 2 VDStent high costs 3 VDStent low costs 2 VDStent low costs 3 VDCABG costs (C)$19.297$24.566$16.638$20.456$21.350 effects (E)81%81%81%81%88% CE ratio$23.876$30.397$20.586$25.322$24.348 Clinically, stenting is not expected to be more effective than CABG, but should be cost effective in both the 2- and 3-VD group when using the lower cost estimate and in the 2 VD group when using the higher cost assumptions.

Angioplasty, Balloon, Coronary↗
PubMed1999

Intracranial hypertension in head injury: management and results.

OBJECTIVE: (1) To describe the pattern of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in a group of severe head-injured patients, (2) to quantify complications of ICP monitoring, and (3) to describe a management protocol and its results. DESIGN: Prospective observational study. SETTING: General intensive care unit in a teaching hospital. PATIENTS: 138 comatose patients, selected according to the following criteria: age > 16 years, coma [Glasgow Coma Scale (GCS) < or = 8] with at least one pupil reactive after resuscitation, digital recording of intracranial and arterial pressure, and jugular saturation measurements. MEASUREMENTS AND RESULTS: Median GCS was 5, and 62 patients had significant extracranial injuries; 71 had intracranial hematomas, which were urgently evacuated. Mean ICP was 20.5 mmHg (SD 8.34), mean CPP was 71.86 mmHg (SD 11.22); cerebral extraction of oxygen averaged 29 %. Medical therapy was used to control ICP in 130 cases; 93 patients required hyperventilation. Vasopressors were infused in 16 cases; in 14 cases a barbiturate infusion was started. In 6 patients all pharmacological treatments failed and surgical decompression was done. The only complication of ICP monitoring was meningitis in 3 patients. Outcome at 6 months was a good recovery and moderate disability for 82 patients (59.4%), severe disability and vegetative status for 37 (26.8%), and 19 patients died (13.7%). The severity of intracranial hypertension was related to poorer results at 6 months. CONCLUSIONS: Intracranial hypertension is very frequent in severe head injury but can be reasonably well controlled by combined surgical and medical therapy.

Adolescent↗
PubMed1999

Impact of new treatments for respiratory failure on outcome of infants with congenital diaphragmatic hernia.

UNLABELLED: Term and near-term newborn infants with congenital diaphragmatic hernia (CDH), symptomatic in the first 24 h of life or diagnosed antenatally, without other significant malformations were treated at our hospital with high-frequency oscillatory ventilation (HFOV) as a primary modality of ventilation and elective delay in surgical repair after a period of stabilisation. When unresponsive to HFOV, infants were treated with surfactant, inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation (ECMO) to achieve pre-operative stabilisation. From October 1994 to August 1998, 28 newborn infants with CDH were managed with such treatment; mean birth weight was 3184 +/- 535 g and gestational age 38.5 +/- 1.85 weeks. Age at operation was 68 +/- 35 h. In 9 cases, large diaphragmatic defects required the use of a prosthetic patch (Gore-tex). HFOV was used for primary ventilation in inborn patients (n = 16); outborn infants (n = 12) were placed on HFOV at admittance. A total of 15 patients (53%) were stabilised using only HFOV. Bovine surfactant was administered in 12 infants and 4 responded. iNO was used in eight infants and five responded. ECMO was used in three outborn patients and one survived. Overall, out of 28 infants, 25 survived (89%). Neurological examination (Amiel-Tison and Grenier) of 15 infants showed transient anomalies at 6 months in 40% of infants, while a normal neurological examination was present in all patients at 1 year. The development quotient (Griffiths scales) was within normal values in ten and mildly abnormal in two infants tested at 1 year. CONCLUSION: Management based on early HFOV, eventually associated with surfactant, iNO and ECMO to achieve preoperative stabilisation, resulted in a good survival rate (89%) and good neurodevelopmental outcome at 1 year of age in infants with CDH.

Animals↗
PubMed1999

Administration of protamine after coronary stent deployment.

BACKGROUND: Prompt reversal of anticoagulation by protamine administration could be an important therapeutic option to treat serious procedural complications such as vessel rupture or major bleeding from the puncture site during coronary stent implantation. However, this therapeutic option is rarely used because of the possible risk of stent thrombosis. METHODS: We retrospectively analyzed the incidence of acute and subacute stent thrombosis and vascular complications in 90 patients who received protamine (protamine group) and 1763 patients who did not receive protamine (control group) after successful coronary stent implantation. The 2 groups were matched for clinical, angiographic, and procedure characteristics. RESULTS: No patients in the protamine group had adverse effects such as hypotension or vascular collapse during protamine administration. Acute stent thrombosis did not occur in any protamine group patient but did occur in 12 patients in the control group (0.7%) (P =.47). Subacute stent thrombosis occurred in 2 patients in the protamine group (2.1%) and in 15 in the control group (0.8%) (P =.20). By logistic regression analysis, protamine was not a determinant of stent thrombosis. CONCLUSIONS: Reversal of anticoagulation by protamine after stent implantation does not predispose to stent thrombosis. This result has important clinical consequences because it allows the use of protamine in the treatment of coronary perforation and serious bleeding complications that may occur during coronary stent deployment.

Aged↗