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Biomedical subjects

M Quintana

Publications and source records attributed to M Quintana.

At least 37 records · Page 2Linked to original sources
PubMed2001

Evaluation of the efficacy of lambda-cyhalothrin applied as ultra-low volume and thermal fog for emergency control of Aedes aegypti in Honduras.

An extended-duration formulation of lambda-cyhalothrin (Demand CS) applied as either an ultra-low volume (ULV) or thermal fog spray from a new handheld sprayer (Terrier) against Aedes aegypti was evaluated in Honduras. Spray applications were made at the front door for 1 min or to each room for 15 sec, both for the ULV and thermal fog applications to houses in separate blocks for each treatment. The efficacy and duration of effectiveness of the spray was determined from sentinel caged mosquito mortality and collection of mosquitoes within houses with a backpack power aspirator. Sentinel caged mosquito mortality in both open and sequestered locations was 97-100% for all spray treatments, with control mortality less than 2%. Both ULV applications (front door and each room) provided 4 wk of significant control (P < 0.01) based on adult Ae. aegypti house collections.

Aedes↗
PubMed2000

Continuous infusion of recombinant activated factor VII during caesarean section delivery in a patient with congenital factor VII deficiency.

Recombinant activated factor VII (rFVIIa) can be used as an alternative therapy in patients with FVII deficiency. However, as the drug has a very short half-life, continuous infusion could be a meaningful administration modality. We report the case of a 30-year-old woman with moderate FVII deficiency and human immunodeficiency virus infection who underwent a caesarean section delivery. She was treated with a continuous infusion of rFVIIa and did not suffer any bleeding complication. The continuous infusion of rFVIIa was a safe and effective therapeutic approach for our patient, maintaining her levels of FVII:C and avoiding bleeding during caesarean section and afterwards.

Adult↗
PubMed1999

Hepatitis G virus infection markers (RNA and anti-E2 antibodies) in a multicenter cohort of hemophiliacs.

BACKGROUND AND OBJECTIVE: To investigate the prevalence and evolution of hepatitis G virus (HGV) infection in hemophiliacs and to correlate evolution of HGV infection markers with immunologic parameters in those patients co-infected with HIV. DESIGN AND METHODS: HGV RNA and anti-E2 antibodies were studied in 124 patients. Serial samples were drawn every 4 months from 1992 to 1996. Lymphocyte subsets including T-helper lymphocytes, T-suppressor lymphocytes, T-cytotoxic lymphocytes, activated T-lymphocytes and natural killer cells were analyzed. RESULTS: Prevalences were 22.6% for HGV RNA and 18.5% for anti-E2. Four patients had both HGV RNA and anti E2, so the overall prevalence of HGV infection in hemophiliacs was 37.9% (11.5% in 200 controls, p<0.0001). After a median follow-up of 36.6 months 20 patients remained HGV RNA positive, whereas HGV RNA had cleared in 8, with an actuarial probability of clearance at 36 months of 34.6%. Only 2 patients developed anti-E2 antibodies. Four patients cleared anti-E2, with an actuarial probability at 36 months of 24.8%. In patients with HIV infection, both lower CD4+ lymphocyte count (p=0.01) or higher CD8+ lymphocyte count (p=0.03) showed predictive value for probability of clearing HGV-RNA. CD4+/CD8+ ratio (p=0.002) was the only variable included in the best model for HGV-RNA disappearance. INTERPRETATION AND CONCLUSIONS: A more accurate estimation of the prevalence of HGV infection can be achieved with the determination of both HGV RNA and anti-E2. Anti-E2 response can be undetectable or transitory after disappearance of HGV-RNA, giving therefore rise to the possibility of underestimating HGV prevalence with currently diagnostic methods. In HIV-positive patients, cellular immune function seems to be involved in the resolution of HGV infection, following the significant correlation found between clearance of HGV-RNA and CD4+/CD8+ lymphocyte populations.

Adolescent↗
PubMed1998

Malaria diagnosis by dipstick assay in a Honduran population with coendemic Plasmodium falciparum and Plasmodium vivax.

A Plasmodium lactate dehydrogenase dipstick designed to separately detect P. falciparum and P. vivax malaria was evaluated in two Honduran populations where both species are endemic. The dipstick was compared to thick film microscopy; the polymerase chain reaction (PCR) was used to analyze discordant results. The dipstick had a sensitivity of 100% and a specificity of 95% compared with microscopy in the diagnosis of Plasmodium infections in a hospital population; the mean parasite density was approximately 590/mm3. In a field sample of mostly asymptomatic volunteers, the sensitivity of the dipstick for Plasmodium infection varied with parasite density. Additionally, the sensitivity and specificity of the dipstick was similar to thick film microscopy in the diagnosis of vivax malaria compared with the PCR. The dipstick was unable to detect P. vivax in the presence of P. falciparum because of cross-reactivity in the pan-specific band. Accurate species identification in mixed infections remains a problem in malaria diagnosis.

Clinical Enzyme Tests↗
PubMed1998

von Willebrand factor contained in factor VIII concentrates of different purities supports platelet adhesion in blood samples from a heterogeneous group of patients with von Willebrand disease.

BACKGROUND AND OBJECTIVE: Plasma derived FVIII-VWF concentrates in which the VWF structure is reasonably maintained are recommended as substitutive therapy in VWD. Our aim was to assess platelet deposition and binding to subendothelial structures of VWF present in FVIII concentrates. DESIGN AND METHODS: Cryoprecipitate (CRY), intermediate-purity (IPC), or high-purity (HPC) FVIII concentrates were added in vitro to citrated blood samples from 11 patients affected by different subtypes of VWD, with the aim of normalizing VWF levels. Measurements of VWF:Ag, ristocetin cofactor (RiCof) activities, FVIII coagulant activity (FVIII:C), and platelet interaction with subendothelium under flow conditions (Baumgartner's perfusion method, computer-assisted morphometry, shear rate 1000 s-1, 10 min, 37 degrees C) were determined. Binding of VWF to the luminal surface of the perfused vessels was assessed by immunofluorescence microscopy. Paired t-test statistics were performed. RESULTS: Addition of FVIII-VWF preparations raised VWF:Ag from baseline (BSL) values of 0.3 (SD 0.2) to averages of 1.4 (SD 0.5, p < 0.001), 1.2 (SD 0.6, p < 0.001), and 0.4 (SD 0.3) IU mL-1 after CRY, IPC, and HPC, respectively. A positive labeling for VWF was observed by immunofluorescence in vessels perfused with blood containing any of the concentrates. Platelet adhesion of 13.2 (SD 7.6), 22.4 (SD 10.8), 24.8 (SD 7.8, p < 0.03), or 22.5 (SD 4.8)% was measured in BSL, CRY, IPC, or HPC tests, respectively. INTERPRETATION AND CONCLUSIONS: Our observations support the hypothesis above the mechanisms involved in the beneficial effects of commercial concentrates in von Willebrand disease: the VWF in these concentrates has functional capacity to bind to subendothelium and to support platelet adhesion.

Adult↗
PubMed1997

Heart rate variability as a means of assessing prognosis after acute myocardial infarction. A 3-year follow-up study.

AIMS: The present study evaluated the prognostic value of heart rate variability after acute myocardial infarction in comparison with other known risk factors. The cut-off points that maximized the hazards ratio were also explored. PATIENTS AND METHODS: Heart rate variability was assessed with 24 h ambulatory electrocardiography in 74 patients with acute myocardial infarction, 4 +/- 2 days after hospital admission and in 24 healthy controls. Patients were followed for 36 +/- 15 months. RESULTS: During follow-up, 18 patients died, nine suffered a non-fatal infarction and 20 underwent revascularization procedures. Heart rate variability was higher in survivors than in non-survivors (P = 0.005). This difference was found at higher statistical levels when comparing non-survivors vs controls (P = 0.0002). A similar statistically significant difference was also found between survivors vs controls (P = 0.04). Patients suffering non-fatal infarction and cardiac events (defined as death, non-fatal infarction or revascularization) had a lower heart rate variability than those without (P = 0.03 and P = 0.03, respectively). With multivariate regression analysis, decreased heart rate variability independently predicted mortality and death or non-fatal infarction. The presence of a left ventricular ejection fraction < 40% and a history of systemic hypertension were, however, stronger predictors. The cut-off points that maximized the hazards ratio using the Cox model differed from those reported by others. CONCLUSION: Decreased heart rate variability independently predicted poor prognosis after myocardial infarction. However, the cut-off points that should be used in clinical practice are still a matter for further investigation.

Adult↗
PubMed1997

Markers of risk after acute myocardial infarction. A comparison of clinical variables, ambulatory and exercise electrocardiography, echocardiography, and stress echocardiography.

BACKGROUND: Short-term mortality after myocardial infarction has decreased continuously among members of selected populations. Nonetheless, the long-term prognosis among members of unselected populations remains bad. Further research in risk stratification is therefore needed. In the present study we tested the additive value of clinical variables, echocadiography, ambulatory electrocardiography, exercise testing, and stress echocardiography in assessing the long-term prognosis after acute myocardial infarction. METHODS: Two-dimensional echocardiography and ambulatory electrocardiography (analysis of ST-segment changes and of heart rate variability) were performed for 74 patients aged < 75 years who had had an acute myocardial infarction. Before their discharge from hospital, 70 patients were subjected to a combined exercise test and stress echocardiography. The time of follow-up was > or = 3 years. RESULTS: During follow-up 18 patients died, and 38 suffered cardiac events defined as death, nonfatal reinfarction and the need for revascularization. We first tested 31 covariates in a univariate regression analysis. A subsequent multivariate analysis was performed in two stages. During the first of these, clinical variables (a history of systemic hypertension, infarct localization, and diabetes mellitus) and variables derived from noninvasive tests (new-onset wall-motion abnormality during stress echocardiography, ST-segment depression and heart-rate variability during ambulatory electrocardiography, the ejection fraction by echocardiography at rest, and the double product during exercise tests) predicted mortality. After the second stage, however, the only remaining independent predictors of mortality were the presence of a new-onset wall-motion abnormality (P < 0.0001, relative risk 13.5, 95% confidence interval 3.6-51.3), ST-segment depression during ambulatory electrocardiography (P = 0.003, relative risk 5.0, 95% confidence interval 1.7-15.7) and a decreased heart rate variability (P = 0.007). CONCLUSIONS: The only variables that were of independent value in assessing the long-term mortality were those expressing residual myocardial ischemia and the cardiovascular sympatho-vagal balance. It is, therefore, recommended that one should monitor these variables for patients recovering from an acute myocardial infarction.

Aged↗
PubMed1996

Antibodies to factor VIII in plasma of patients with hemophilia A and normal subjects.

Non-neutralizing factor VIII (FVIII) antibodies (FVIII-Ab) in hemophilia A may be associated with an abnormal clinical response to FVIII concentrates. Patients with FVIII inhibitors may develop noncoagulation FVIII-Ab after the induction of immunotolerance. Natural FVIII-Ab may be detected in the plasma of some healthy subjects. The aim of this study was to analyze the presence of FVIII-Ab in the plasma of 53 normal blood donors and 124 patients with hemophilia A (18 patients had a previous history of FVIII inhibitor, but only 12 had inhibitor at the moment this study was performed). FVIIII inhibitor was measured using the Bethesda method. FVIII-Ab were analyzed by a specific ELISA assay using purified FVIII from a monoclonal concentrate and a standard plasma containing 26 Bethesda units (BU) of FVIII inhibitor. Purified FVIII was used to coat wells of a microtiter plate and was incubated with dilutions of plasma to be tested. Bound human IgG FVIII-Ab were detected by incubation with polyclonal sheep anti.human IgG alkaline phosphatase conjugate, and the OD405 was quantitated. A linear fit was obtained (by plotting FVIII-Ab positivity [OD 405nm] versus BU titer) when serial dilutions of this standard inhibitor plasma, containing titers of 0.5 BU or higher, were used. Four different levels of FVIII-Ab positivity [OD 405nm] were distinguished in this assay: Negative levels (-) were obtained with dilutions of the standard inhibitor containing < 0.5 BU. Mild levels (+) were obtained with dilutions of 0.5-5 BU. Moderate levels (+2) were obtained for dilutions ranging from 5-25 BU. Maximum positivity (+3) was obtained for dilutions of titers > 25 BU. FVIII-Ab positivity was detected in eight of the normal subjects (15%): three were found to be moderately positive (+2) and five mildly positive (+). No inhibitory activity was detectable when whole plasma was used. All the hemophilic patients with a presence of FVIII inhibitor at the time of the study were found to be positive for FVIII-Ab. In addition, the level of positivity correlated with the corresponding BU. Four of the six patients who had a history of inhibitory were negative and two positive. Twenty additional patients (16.12%) in whom no inhibitory activity was detected were found to be positive for FVIII-Ab: 16 + and four +2. The mean age of patients with FVII-Ab positivity was significantly higher than that of patients of the FVIII-Ab negative group (p < 0.005). In conclusion, FVIII-Ab positivity in patients with hemophilia A was 17.7% higher than the level of positivity detected by an inhibitory assay. We propose that this method for FVIII-Ab analysis could be used for patients with hemophilia A, at least to complement the functional inhibitor assay. FVIII recovery or half-life should be assessed in patients who test positive for FVIII-Ab and who show no evidence of inhibitor.

Adolescent↗
PubMed1996

[Parainfectious transverse myelitis in an adolescent. Difficulties in the etiological diagnosis].

A diagnostic process in a 13 year-old boy with a parainfectious transverse myelitis is described. Its onset was acute, with L1-location level of lesion. After a mild improvement, a relapse happened 26 days later, with a D6 level and without subsequent recovery. It has not been found criteria for diagnosis of multiple sclerosis, nor data suggesting a vascular or ischaemic anomaly. Likewise, other causes and specific infections were rejected, being cataloguet as parainfectious etiology, due a previous viral infection before its onset.

Acute Disease↗
PubMed1995

Prognostic value of predischarge exercise stress echocardiography after acute myocardial infarction.

A predischarge exercise test was performed by 70 patients 7 +/- 4 days (mean +/- SD) after acute myocardial infarction (AMI) to determine the short- and long-term prognostic value of predischarge exercise stress echocardiography (Ex-Echo) compared with exercise stress electrocardiography (Ex-ECG). Two-dimensional echocardiograms were obtained at rest and immediately after exercise; a wall motion score index was obtained both at rest and immediately after exercise. Results of the Ex-Echo were positive in 27 patients (39%), whereas those of Ex-ECG were positive in 34 (49%). The wall motion index after exercise was lower in patients who died during follow-up (85 vs 98, p = 0.01) and in those with cardiac events, defined as death, nonfatal reinfarction, or revascularization (88 vs 98, p = 0.005). More patients with a positive Ex-Echo result had short-term cardiac events (within 2 weeks) than patients with a negative Ex-Echo (6 [22%] vs 2 [5%], p = 0.04). The same was true for long-term mortality (12 [44%] vs 3 [7%], p = 0.0002), reinfarctions (10 [37%] vs 4 [9%], p = 0.01), revascularization procedures (11 [41%] vs 7 [16%], p = 0.023), and cardiac events (22 [81%] vs 12 [28%], p < 0.0001). Survival time was shorter in patients with positive compared with negative Ex-Echo results (34% difference between groups, 95% confidence interval [CI] 10% to 58%, p = 0.002). The same applied for cumulative survival free from cardiac events (43%, p = 0.001, 95% CI 9% to 77%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

Assessment and significance of ST-segment changes detected by ambulatory electrocardiography after acute myocardial infarction.

This study assessed the prognostic value of ST-segment changes detected by ambulatory electrocardiographic monitoring during the early in-hospital period after acute myocardial infarction. New methods for defining the ST-segment reference level and for measuring ST-segment elevation were used. ST-segment depression was defined as a change in ST level by > or = 0.1 mV 80 ms after the J point, elapsing > or = 1 minute. ST-segment elevation was defined as a deviation by > or = 0.15 mV, elapsing > or = 1 minute, and measured at the J point. An interval of > or = 2 minutes was required before another discrete episode was counted. Four ST-segment reference levels were automatically calculated: (1) "isoelectric," (2) "nearest to normal," (3) "24-hour median," and (4) "first-hour median." During a mean follow-up period of 3 years (mean 36 +/- 15 months), 47 cardiac events occurred in 38 patients: 18 deaths, 9 nonfatal reinfarctions, and 20 revascularization procedures. More deaths occurred in patients with than without ST elevation-24-hour median (22% vs 5%, p = 0.03), and in patients with than without ST depression-isoelectric (61% vs 32%, p = 0.02), and in patients with than without ST-depression-24-hour median (61% vs 23%, p = 0.003). "All cardiac events" (deaths, infarctions, or revascularization procedures) occurred more often in patients with than without ST depression-isoelectric (55% vs 22%, p = 0.003), and in patients with than without ST-depression-24-hour median (47% vs 17%, p = 0.004). Sensitivity, specificity, and accuracy of ST depression/elevation-24-hour median to assess mortality were 78%, 71%, and 73%, respectively.

Aged↗