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J P Collet

Publications and source records attributed to J P Collet.

At least 37 records · Page 2Linked to original sources
PubMed2002

Tattooing and risk for transfusion-transmitted diseases: the role of the type, number and design of the tattoos, and the conditions in which they were performed.

Tattoos have been shown to be associated with transfusion-transmitted diseases (TTDs), particularly hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. Very little is known about the association between different categories of tattoos and TTDs. In a cross-sectional study in Brazil, we studied 182 individuals with tattoos and assessed the odds of testing positive for a TTD according to tattoo type, number, design and performance conditions. Major findings were significant associations between an increasing number of tattoos and HBV infection (odds ratio (OR) of 2.04 for two tattoos and 3.48 for > or = 3 tattoos), having a non-professional tattoo and testing positive for at least one TTD (OR = 3.25), and having > or = 3 tattoos and testing positive for at least one TTD (OR = 2.98). We suggest that non-professional tattoos and number of tattoos should be assessed as potential deferral criteria in screening blood donors.

Adolescent↗
PubMed2001

Effects of Abciximab on the architecture of platelet-rich clots in patients with acute myocardial infarction undergoing primary coronary intervention.

BACKGROUND: Abciximab plus aspirin improves the TIMI 3 flow rate of the infarct-related artery in patients treated with either percutaneous coronary intervention or thrombolysis. The present study investigated whether the reperfusion efficacy of abciximab relates to modifications of clot architecture in patients admitted for acute myocardial infarction (AMI). METHODS AND RESULTS: A total of 23 AMI patients in the Abciximab before Direct angioplasty and stenting in Myocardial Infarction Regarding Acute and Long term follow-up (ADMIRAL) trial received, in a double-blind fashion, either abciximab (n=13) or placebo (n=10) before primary stenting. Viscoelastic (G' in dyne/cm(2)) and morphological (mean platelet aggregate surface area [SAG] in micrometer(2)) indexes of ex vivo platelet-rich clots (PRC) were assessed in a double-blind fashion before and after the bolus administration of abciximab or placebo. G' and SAG reflect the mechanical and morphological impact of activated platelets on the PRC fibrin network, respectively. Abciximab administration reduced G' by 63% (P=0.0001) and SAG by 65% (P=0.0007), and no effect was seen in the placebo group. These abciximab-related changes increased fibrin exposure as a consequence of the platelet-aggregate surface reduction and may have improved endogenous fibrinolysis. These effects were identified in all patients, independent of previous heparin administration. CONCLUSIONS: Abciximab dramatically reduces platelet aggregate size and increases the fibrin accessibility of ex vivo PRC in AMI patients. These modifications could participate in the better coronary artery patency observed with abciximab.

Abciximab↗
PubMed2001

Hyperbaric oxygen for children with cerebral palsy: a randomised multicentre trial. HBO-CP Research Group.

BACKGROUND: The use of hyperbaric oxygen for children with cerebral palsy has spread worldwide, despite little scientific evidence of efficacy. We did a randomised trial to assess the efficacy and side-effects of this form of therapy in children with cerebral palsy. METHODS: 111 children with cerebral palsy aged 3-12 years were randomly assigned hyperbaric oxygen (n=57) or slightly pressurised room air (n=54). All children received 40 treatments over 2 months. Hyperbaric oxygen treatment was 1 h in 100% oxygen at 1.75 atmospheres absolute (ATA); children on slightly pressurised air received air at 1.3 ATA (the lowest pressure at which pressure can be felt, thereby ensuring the maintenance of masking). The main outcome measure was gross motor function. Secondary outcomes included performance in activities of daily living, attention, working memory, and speech. FINDINGS: For all outcomes, both groups improved over the course of the study, but without any difference between the two treatments. The score on the global gross motor function measure increased by 3.0% in the children on slightly pressurised air and 2.9% in those on hyperbaric oxygen. The mean difference between treatments was -0.40 (95% CI -1.69 to 0.90, p=0.544). Other changes were seen in speech, attention, memory, and functional skills. Ear problems occurred in 27 children treated by hyperbaric oxygen and in 15 treated with hyperbaric air (p=0.004). INTERPRETATION: In this study, hyperbaric oxygen did not improve the condition of children with cerebral palsy compared with slightly pressurised air. The improvement seen in both groups for all dimensions tested deserves further consideration.

Cerebral Palsy↗
PubMed2001

Percutaneous coronary intervention after subcutaneous enoxaparin pretreatment in patients with unstable angina pectoris.

BACKGROUND: Subcutaneous low-molecular-weight (LMW) heparins can effectively replace unfractionated heparin in patients with unstable angina or non-Q-wave myocardial infarction. However, the optimal anticoagulation strategy for these patients when they require cardiac catheterization is still unclear. Therefore, we evaluated a new and simple strategy of anticoagulation in these patients. METHODS AND RESULTS: A total of 451 consecutive patients with unstable angina/non-Q-wave myocardial infarction were treated for at least 48 hours with subcutaneous injections of enoxaparin (1 mg [100 IU]/kg every 12 hours, cycled at 6 AM and 6 PM). Of this unselected population, 293 patients (65%) underwent a coronary angiography within 8 hours of the morning LMW heparin injection, followed by immediate percutaneous coronary intervention (PCI) in 132 patients (28%). PCI was performed without any additional bolus of unfractionated/LMW heparin and without coagulation monitoring. Anti-Xa activity at the time of catheterization was 0.98+/-0.03 IU/mL, was >0.5 IU/mL in 97.6% of patients, and did not relate to the LMW heparin injection-to-catheterization time. There were no in-hospital abrupt closures or urgent revascularizations after PCI. The death/myocardial infarction rate at 30 days was 3.0% in the PCI group (n=132) but 6.2% in the whole population (n=451) and 10.8% in the patients not undergoing catheterization (n=158). The 30-day major bleeding rate was 0.8% in the PCI group, which was comparable to that of patients without catheterization (1.3%). CONCLUSIONS: PCI within 8 hours of the last enoxaparin subcutaneous injection seems to be safe and effective. The safety of subcutaneous LMW heparin in combination with platelet glycoprotein IIb/IIIa blockade awaits further study.

Aged↗
PubMed2001

Enoxaparin in unstable angina patients with renal failure.

The dosage of the subcutaneous low molecular weight heparin enoxaparin in unstable angina patients undergoing coronary angiogram and coronary angioplasty depends clearly on the renal function. It should be significantly reduced to 64% of the standard dose (1 mg/kg per 12 h) in patients with severe renal failure (creatinine clearance<30 ml/min) to provide a safe anticoagulant profile.

Aged↗
PubMed2001

Disaggregation of in vitro preformed platelet-rich clots by abciximab increases fibrin exposure and promotes fibrinolysis.

The glycoprotein IIb/IIIa receptor inhibitor abciximab has been shown to facilitate the rate and the extent of pharmacological thrombolysis with recombinant tissue plasminogen activator (rtPA) in patients with acute myocardial infarction. However, the underlying mechanisms remain not fully determined. We sought to demonstrate that this facilitating effect of abciximab could be related to its potential to modify the clot architecture and the clot physical properties. Compared with fibrin-rich clots, platelets dramatically modified the in vitro properties of the fibrin network, leading to a significant increase of the permeability (K(s)) and the viscoelasticity (G') indexes but also leading to the appearance of platelet aggregates (surface area [S.ag]). These modifications resulted in a 2.6-fold decrease of the fibrinolysis rate when rtPA (1 nmol/L) was added before the initiation of clotting. Adding aspirin (100 microgram/mL) or abciximab (0.068 micromol/L) before the clotting of platelet-rich clots (PRCs) lowered K(s) by 50% and 70%, respectively (P<0.01), G' by 41% and 66%, respectively (P<0.01), and S.ag by 32% and 61%, respectively (P<0.01). As a consequence, the lysis speed was increased by 21% with aspirin (P<0.01) and 45% with abciximab (P<0.01). However, unlike aspirin, permeation of preformed PRCs with abciximab (0.068 micromol/L) decreased G' (37%, P<0.01), K(s) (35%, P<0.001) and S.ag (25%, P=NS) and resulted in a 27% (P<0.01) increase of the lysis speed when abciximab and rtPA (0.2 micromol/L) were simultaneously permeated. This effect was found to be time dependent and was observed only with early permeation, starting within the first 10 minutes of clotting. These changes in the physical properties of the PRC architecture suggest that fibrin is removed from the platelet-fibrin aggregates and reexposed into the surrounding fibrin network, increasing rtPA access to fibrin and therefore the fibrinolysis rate. The superiority of abciximab over aspirin in accelerating fibrinolysis of forming and preformed PRCs is related to its ability to modulate the interactions of fibrinogen and fibrin with platelets. These findings provide new mechanistic information on reperfusion therapy.

Abciximab↗
PubMed2001

Lessons learned: Outcomes and methodology of a coping skills intervention trial comparing individual and group formats for patients with cancer.

OBJECTIVE: Nucare, a short-term psychoeducational coping skills training intervention was evaluated in a randomized controlled clinical trial (RCT) of 225 newly diagnosed breast and colon cancer patients. METHOD: Measures of psychosocial distress, well being and optimism were evaluated every four months during a one-year period. Patients were randomized to one of four arms: Nucare presented in an individual basis; Nucare presented in a group format; a non-directive supportive group; and a no-intervention control. The interventions were provided in five sessions of ninety minutes each. RESULTS: Patients with breast cancer who received Nucare presented in an individual format showed more significant improvements in well-being over time compared to those in the control and group arms. CONCLUSIONS: We were unable to develop functioning groups within the RCT. Partial explanations for the latter finding include the structural limitations of the RCT: the groups were small, difficult to schedule and patients indicated that they would have preferred to choose whether or not to participate in a group. The positive changes in women with breast cancer who received Nucare persisted at 12 months.

Adaptation, Psychological↗
PubMed2001

Selection of subjects for hospital-based epidemiologic studies based on outward manifestations of disease.

Selection of controls with the same outward manifestations of disease as the case group has been proposed as a means of avoiding selection bias in hospital-based case-control studies. The same strategy, however, can lead to selection bias in registry-based case-control studies that use control diseases with similar manifestations whose diagnoses might have been associated with the exposure. Matching exposed and unexposed subjects by outward manifestation of disease can be used in cohort and cross-sectional studies aiming at decreasing selection bias. This strategy in these study designs may lead to overmatching, but this will not bias the relative-risk estimates. Efficiency considerations in applying this strategy require further investigation.

Bias↗
PubMed2001

[Review and future perspectives on low-molecular-weight heparin].

Low molecular weight heparins appear to be a better choice in patients with unstable angina than unfractionated heparin. Their favourable pharmacokinetic profile allows an excellent predictable dose-response with a subsequent rapidly effective and stable anticoagulation, which is ideal in the setting of percutaneous coronary intervention. Although direct comparisons between LMWH and UH are limited, substantial evidence exists that patients receiving LMWH can be safely brought to cardiac catheterization. Therefore, previous concern regarding transitioning such therapy from the medical service to the cardiac catheterization laboratory should not impede the upstream use of these agents. Direct i.v. injection of LMWH in the setting of elective PCI have also been shown to be safe and effective. Although UH remains an option in conjunction with GP IIb/IIIa inhibitors, there is substantial evidence that LMWH and GP IIb/IIIa inhibitor therapy can be used safely in combination. Patients with either chronic renal failure, mechanical valves or atrial fibrillation are other important issues which deserve additional prospective evaluation of the safety and the efficacy of LMWH. Development of a biological assay for monitoring either LMWH or GP IIb/IIIa receptor antagonists is another important issue in the setting of antithrombotic combinations which are now commonplace.

Angina, Unstable↗
PubMed2000

Thrombotic dysfibrinogenemia. Fibrinogen "Caracas V" relation between very tight fibrin network and defective clot degradability.

Fibrinogen Caracas V is a thrombotic dysfibrinogenemia with an Aalpha 532 Ser-->Cys mutation characterized by a tight fibrin network formed of thin fibers responsible for a less porous clot than a normal one. In the present work, fibrinogen Caracas V is further characterized in order to understand the relationship between the structural defect and thrombophilia. This thrombotic disorder has been attributed to a tight fibrin network responsible for a decreased permeation of flow through the clot, leading to defective thrombus lysis due to a diminished availability of fibrinolytic enzymes to the inner fibrin surface. Correction of clot structure anomaly, by addition of dextran 40 to fibrinogen before clotting, induces an improvement in fibrin degradation that was attributed to an increase in porosity. The pulmonary embolism observed in this family has been related to an hyper rigidity of the clot, an anomaly that is also corrected by dextran. Furthermore, this abnormal fibrinogen binds more albumin than does normal fibrinogen, a phenomenon attributed to the mutation of serine in Aalpha-532 by cysteine. Therefore, this fibrinogen shows a striking similarity to the fibrinogen Dusart, allowing us to confirm that the alphaC-terminal part of fibrinogen plays an important role in fibrin structure, and to conclude that the anomaly of fibrin network observed in fibrinogen Caracas V is responsible for a deficient thrombus lysis.

Albumins↗
PubMed2000

[Limitations of clinical trials].

The major limitation of randomized clinical trials is their restriction to interventions that are supposed to have a positive effect. Another limit is related to the difficulty to interpret or generalize the results because the studied population is very different from the population treated in normal life. Participating in a trial may also influence the results. Limitation also includes the specificity of the questions answered; the narrow perspective of many trials leaves aside important information related to the consequences of the intervention on quality of life, satisfaction or costs. Clinical trials usually do not provide the answers to the questions asked by practitioners and deciders. A solution consists in developing disease management approach which may include thousands of patients with the implementation of trials in real life with a long duration of follow-up.

Evidence-Based Medicine↗
PubMed2000

Low molecular weight heparin after mechanical heart valve replacement.

BACKGROUND: Patients with mechanical heart valves require life-long anticoagulation. We report here the first large and comparative series of consecutive patients anticoagulated with low molecular weight heparin (LMWH) after mechanical heart valve replacement. METHODS AND RESULTS: In this comparative, nonrandomized study, 208 consecutive patients who underwent a single or double heart valve replacement with mechanical prostheses were anticoagulated subcutaneously with unfractionated heparin (UH) in the first period (n=106) and LMWH in the second phase (n=102) of the study. Baseline characteristics were similar in the 2 groups. The mean durations of UH and LMWH treatments were 13.6+/-0.5 and 14.1+/-0.6 days, respectively (not significant). On the second day of treatment, 87% of patients treated with LMWH had an anti-Xa activity within the range of efficacy (0.5 to 1 IU/mL), but only 9% of UH-treated patients had an activated partial-thromboplastin time value within the therapeutic range (1.5 to 2.5 times control, P<0.0001 between the 2 groups). On the last day of prescription, all LMWH-treated patients had anti-Xa activity above 0.5 IU/mL, but 19% were above 1 IU/mL. In the UH group, 27% of patients had an activated partial-thromboplastin time above 1.5 times control, but 62% were overanticoagulated. Two major bleedings occurred in each group, and one stroke occurred in the UH group. CONCLUSIONS: In this first comparative study, anticoagulation with LMWHs after mechanical heart valve replacement appears feasible, provides adequate biological anticoagulation, and compares favorably with UH anticoagulation. Randomized studies are now needed to further evaluate this new therapeutic approach.

Anticoagulants↗
PubMed2000

Coordination of primary health care for back pain. A randomized controlled trial.

STUDY DESIGN: A randomized controlled trial comparing usual care with a program for the coordination of primary health care (CORE) for the treatment of subacute low-back pain patients. OBJECTIVES: To measure the effectiveness of the CORE program as a mean for implementing clinical practice guidelines for low-back pain in an urban community. SUMMARY OF BACKGROUND DATA: Clinical practice guidelines have been developed for primary care physicians and patients on the clinical management of low-back pain. The implementation of the guidelines in a large community is difficult with the multiplicity of medical and nonmedical back care providers and products. The CORE program was designed to make the guidelines fit in this complex environment. METHODS: One hundred ten workers compensated for low-back pain for 4 to 8 weeks in metropolitan Montreal were randomized in two groups: usual care (N = 56) and the CORE program (N = 54). Coordination of primary health care was performed by two primary care physicians and a nurse in liaison with the treating physicians, and included a complete examination, recommendations for the clinical management, and support to carry out the recommendations. All workers were followed for 6 months. Back pain and functional status were assessed at baseline, 3 months, and 6 months. RESULTS: In the 6-month follow-up, the CORE group returned to work 6.6 days (standard error = 8.9) quicker than the control group, a difference that was not statistically significant. However, the CORE group showed a sustained improvement in pain and functional status with two-fold differences at the end of the 6 months of follow-up. This represented nine points on the Oswestry scale (P = 0.02) and 12 points on the Quebec Back Pain Disability Scale (P = 0.01). The CORE group also used three times less specialized imaging tests of the spine at 3 months (P < 0.01) and exercised twice as much at 6 months (P < 0.05) than the controls. CONCLUSIONS: The therapeutic results for workers with low-back pain could be improved by implementing the clinical practice guidelines with primary care physicians in a large community, without delaying the return to work. The CORE intervention for back pain patients is highly relevant to primary care practice. It is simple in its application, flexible to accommodate physicians' and- patients' preferences in health care, and it is effective on patients' clinical outcome.

Adult↗
PubMed2000

Effects of various anticoagulant treatments on von Willebrand factor release in unstable angina.

OBJECTIVES: We tested the hypothesis that different anticoagulant treatments may produce different platelet effects and von Willebrand factor (vWf) release in unstable angina. BACKGROUND: The early increase of vWf has been reported to be a risk factor for adverse outcome in unstable angina. Anticoagulant drugs play a key role in stabilization of unstable angina, but they may not have the same efficacy and the same effects on acute vWf release. METHODS: We studied 154 patients enrolled in several clinical trials testing four different anticoagulant treatments in unstable angina or non-Q-wave myocardial infarction. Patients were treated during at least 48 h by either intravenous unfractionated heparin, one of two different low molecular weight heparins (enoxaparin or dalteparin) or the direct thrombin inhibitor PEG-hirudin. All patients received aspirin but no Ib/IIIa inhibitors. RESULTS: The release of vWf over the first 48 h (delta vWf) did not relate to the baseline clinical characteristics. At 30 days of follow-up, delta vWf was sevenfold higher in patients with an end point (death, myocardial infarction, revascularization) than in patients free of events (+53 +/-7% vs. +7 +/-14%, p = 0.004). The same trend was present for each component of the composite end point with the highest levels for one-month mortality (+87 +/- 32% vs. +26 +/- 8%, p = 0.09). The vWf values did not increase over 48 h in patients receiving either enoxaparin or PEG-hirudin (+10 +/- 9% and -5 +/- 20%, respectively). A serious rise ofvWf was measured in unfractionated heparin-treated patients (+87 +/- 11%), which differed significantly from the enoxaparin group (p = 0.0006) and PEG-hirudin group (p < 0.0001). In dalteparin-treated patients, delta vWf was elevated (+48 +/- 8%) and did not differ from the unfractionated heparin group (NS). CONCLUSIONS: We confirm that, in unstable angina patients, a rise of vWf over the first 48 h is associated with an impaired outcome at 30 days. Moreover, the four different anticoagulant treatments tested here do not provide the same protection with regards to vWf release, which may have important prognostic implications and explain different results observed in recent clinical trials.

Aged↗
PubMed2000

Comparison between two common methods for reporting cold and diarrhoea symptoms of children in daycare centre research.

BACKGROUND: The increasing number of children attending day care centres (DCCs) in industrialized countries has refocused attention on the occurrence of infections and infectious diseases in these settings. OBJECTIVE: To evaluate the agreement between two methods (parent method vs. educator method) for reporting the occurrence of respiratory and diarrhoeal infections. METHODS: Fifty-two DCCs in Quebec, Canada, participated. Both educators and parents were invited to fill in calendars on which they would indicate the occurrence of colds and diarrhoea. For the parents' method, parents were telephoned biweekly to record their calendar information. For the educators' method, educators returned their calendar pages monthly (following prompting by phone, when necessary). RESULTS: Three hundred and thirty-three parents of toddlers participated in the 15-month reporting period between September 1996 and November 1997. The average agreement between the two methods was low (13.5% for colds and 9.8% for diarrhoea). Overall estimates of the incidence rates of respiratory and diarrhoeal infections based on parents' method were higher than those based on educators' method. CONCLUSIONS: Parents' data lead to larger estimations of incidence rates and are probably more valid than educators' data.

Child Day Care Centers↗
PubMed2000

Nested case-control study of the effects of non-steroidal anti-inflammatory drugs on breast cancer risk and stage.

We carried out a nested case-control study to measure the rate ratio (RR) for invasive female breast cancer in relation to non-steroidal anti-inflammatory drug (NSAID) use. The source population consisted of the female beneficiaries of the Saskatchewan Prescription Drug Plan from 1981 to 1995 with no history of cancer since 1970. Four controls/case, matched on age and sampling time, were randomly selected. Dispensing rates during successive time periods characterized NSAID exposure. RRs associated with exposure during each period were adjusted for exposure during the others. Confounding by other determinants was studied in analyses adjusted with data obtained by interviewing samples of subjects accrued from mid-1991 to mid-1995. We accrued 5882 cases and 23,517 controls. Increasing NSAID exposure 2-5 years preceding diagnosis was associated with a trend towards a decreasing RR (P-trend = 0.003); for the highest exposure level RR = 0.76, 95% confidence interval 0.63-0.92. This protective effect could not be attributed to confounding by other determinants. In analyses involving only the cases, NSAID exposure 2-5 and 6-10 years preceding diagnosis was associated with significantly reduced risks of presenting with a large tumour (> 5 cm diameter) or distant metastasis, but not regional lymph node metastasis. The use of NSAIDs may retard the growth of breast cancers and prevent distant metastasis.

Adult↗
PubMed2000

Influence of fibrin network conformation and fibrin fiber diameter on fibrinolysis speed: dynamic and structural approaches by confocal microscopy.

Abnormal fibrin architecture is thought to be a determinant factor of hypofibrinolysis. However, because of the lack of structural knowledge of the process of fibrin digestion, relationships between fibrin architecture and hypofibrinolysis remain controversial. To elucidate further structural and dynamic changes occurring during fibrinolysis, cross-linked plasma fibrin was labeled with colloidal gold particles, and fibrinolysis was followed by confocal microscopy. Morphological changes were characterized at fibrin network and fiber levels. The observation of a progressive disaggregation of the fibrin fibers emphasizes that fibrinolysis proceeds by transverse cutting rather than by progressive cleavage uniformly around the fiber. Plasma fibrin clots with a tight fibrin conformation made of thin fibers were dissolved at a slower rate than those with a loose fibrin conformation made of thicker (coarse) fibers, although the overall fibrin content remained constant. Unexpectedly, thin fibers were cleaved at a faster rate than thick ones. A dynamic study of FITC-recombinant tissue plasminogen activator distribution within the fibrin matrix during the course of fibrinolysis showed that the binding front was broader in coarse fibrin clots and moved more rapidly than that of fine plasma fibrin clots. These dynamic and structural approaches to fibrin digestion at the network and the fiber levels reveal aspects of the physical process of clot lysis. Furthermore, these results provide a clear explanation for the hypofibrinolysis related to a defective fibrin architecture as described in venous thromboembolism and in premature coronary artery disease.

Fibrin↗