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T Quiroga

Publications and source records attributed to T Quiroga.

At least 19 recordsLinked to original sources
PubMed2004

Template bleeding time and PFA-100 have low sensitivity to screen patients with hereditary mucocutaneous hemorrhages: comparative study in 148 patients.

OBJECTIVES AND PATIENTS: We compared the template bleeding time (BT) and closure time (CT) in the PFA-100 as screening tests in 148 consecutive patients with unequivocal mucocutaneous bleeding and positive family history. EXCLUSION CRITERIA: drug intake, concomitant diseases including minor infections, low platelet count, diseases of secondary hemostasis. RESULTS: Type 1 von Willebrand disease (VWD-1) was diagnosed in 26 patients, primary platelet secretion defect (PSD) in 33, VWD-1 + PSD in nine, whereas 80 patients did not comply with the criteria for known hemostatic disorders (UD, unknown diagnosis). BT and CT were prolonged in 35.8% and 29.7% of all the patients, respectively (P = 0.23). Sensitivity increased to 48% if an abnormality of BT and/or CT was considered. Same comparisons for BT and CT in each diagnostic category were, respectively: 42 vs. 61.5% in VWD-1 (P = 0.18), 42 vs. 24% in platelet secretion defects (P = 0.11), 67 vs. 89% in VWD-1 + PSD (P = 0.50), and 27.5 vs. 15% in UD (P = 0.06). CONCLUSION: Both tests were relatively insensitive and not significantly different in detecting incoming patients with mucocutaneous hemorrhages. In patients with VWD-1, the PFA-100 performed slightly better, whereas the opposite occurred in those patients with platelet secretion defects. In the UD group, both tests lost sensitivity, but the BT detected 1.8 times more patients than the PFA-100. Given the large proportion of undiagnosed bleeders and the overall low sensitivity of these tests, clinical decisions still rely on the medical history and etiological diagnosis of the bleeding disorder.

Bleeding Time↗
PubMed2001

Increased activation of protein C, but lower plasma levels of free, activated protein C in uraemic patients: relationship with systemic inflammation and haemostatic activation.

Chronic renal failure (CRF) courses with both systemic inflammatory reaction and haemostatic activation. We explored the relationship of these processes with plasma levels of free, activated protein C (APC) and complexes of APC with its inhibitors in patients with CRF under conservative treatment. Plasma concentrations of inflammatory cytokines [tumour necrosis factor alpha (TNFalpha) and interleukin 8], acute-phase proteins (C-reactive protein, fibrinogen, alpha1-anti-trypsin and von Willebrand factor), and markers of haemostatic activation (thrombin-anti-thrombin complexes, plasmin-anti-plasmin complexes, and fibrin and fibrinogen degradation products) were higher in patients than in controls. Inflammatory and haemostatic markers were significantly and positively correlated. Total plasma APC and APC:alpha1-anti-trypsin (alpha1AT) complexes were 44% and 75% higher in patients than in controls (P = 0.0001), whereas free APC was 20% lower (P < 0.015). No significant difference was observed in APC:protein C inhibitor (PCI) complexes between both groups. The free/total APC ratio was significantly lower in patients than in controls (P < 0.0001). Total plasma APC and APC:alpha1AT were positively correlated with activation markers of haemostasis and acute-phase proteins, whereas free APC was inversely correlated with plasma levels of creatinine, acute-phase proteins and fibrin degradation products (FnDP). Systemic inflammation and activation of haemostasis are interrelated processes in CRF. APC generation was increased in response to elevated thrombin production, but the inflammatory reaction, associated with increased synthesis of alpha1AT, reduced its anticoagulant effect. Lower free plasma APC in CRF may be pathogenically associated with atherothrombosis, a major cause of death in this disease.

Adult↗
PubMed2001

Effect of angiotensin-converting enzyme inhibition on renal filtration surface area in hypertensive rats.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitor treatment leads to protective effects on the cellular structure of the glomerulus and the kidney. The aim of this study was to determine whether ACE inhibition increases renal filtration surface area in the spontaneously hypertensive rat (SHR). METHODS: SHR were treated with the ACE inhibitor perindopril at a high dose (3 mg/kg/day) or a low dose (0.1 mg/kg/day) during the period of hypertension development, from 7 to 14 weeks of age. Some animals were treated concomitantly with the bradykinin B2 receptor antagonist, S16118. Tail-cuff systolic blood pressure and body weights were measured twice weekly. At termination of treatment, glomerular number and volume, length, and surface area of glomerular capillaries and renal filtration surface area were estimated using unbiased stereological techniques. RESULTS: There were significant dose-related reductions in blood pressure with high- and low-dose perindopril treatment. Neither low- nor high-dose perindopril treatment had any effect on glomerular number or size or glomerular capillary length and surface area. Hence, there was no significant difference in total renal filtration surface area between any of the experimental groups (8721 +/- 610 mm2 in untreated SHR and 7879 +/- 338 mm2 and 8767 +/- 437 mm2 in the low and high dose perindopril-treated groups, respectively). Coadministration of the bradykinin antagonist did not affect any of the glomerular parameters. CONCLUSIONS: ACE inhibition during the period of hypertension development does not lead to an enhanced glomerular capillary growth or increases in total renal filtration surface area in this model.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2001

[Carbohydrate deficient transferrin, gammaglutamyl transferase and mean corpuscular volume in the evaluation of recent alcohol intake in excessive drinkers].

BACKGROUND: There are no reliable markers to detect heavy drinking or as a tool to control abstinence compliance in alcoholic treatments. The Mean Corpuscular Volume (MCV), and the gammaglutamyl transpeptidase (GGT), are widely used although their predictive value is somewhat limited due to their low specificity. On the other hand, the Carbohydrate-deficient transferrin (CDT) described in the eighties is highly specific and would be of value in early detection of problem drinking. AIM: To compare the sensitivity and specificity of CDT, GGT, and MCV in order to evaluate their single and combined use as markers for detection of heavy drinking behaviour. PATIENTS AND METHODS: CDT, GGT, and MCV values were determined in blood samples from (a) alcoholics (drinking more than 100 9 alcohol/day; n = 47) and (b) healthy volunteers, teetotalers from the Church of Saints of Later Days (n = 34). At the time of sampling alcoholics were presently drinking or had been abstinent for no more than six weeks. ROC curves were used to determine the best cut-off point for each marker. RESULTS: Sensitivity was found to be similar for all three markers. Specificity was found higher for GGT (90.9%) and CDT (91.0%). The combined use of MCV, GGT and CDT, that is, when at least one of the markers is altered, was shown to detect 83% of the patients. No correlation was observed between the markers and the level of alcohol intake. CONCLUSIONS: CDT could be of value as a marker to detect heavy drinking when used with GGT and MCV values combined. CDT is particularly higher in drinking alcoholics and remains significantly high for at least six weeks after they stop drinking.

Adult↗
PubMed1997

[Skin and mucous membrane hemorrhages: clinical assessment, study sequence and relative frequency of hereditary diseases of the hemostasis in a Chilean population].

BACKGROUND: Skin and mucous membrane hemorrhages are distinctive manifestations of hereditary diseases of primary hemostasis and, among them, the different types of von Willebrand disease and of platelet function disorders are the most prevalent. AIM: To know the relative frequency of these disorders and to know the clinical features of patients with mucocutaneous hemorrhages. PATIENTS AND METHODS: Five hundred eighty nine patients whose main symptom was the presence of mucocutaneous hemorrhages were studied. Bleeding time, platelet count, coagulant activity of factor VIII (FVIII:C), FvW: Ag and FvW: CoRis and ABO blood group were measured in all patients in a first stage. According to the results of these tests, further studies were decided. RESULTS: In patients younger than 13 years old, male predominated and, in older patients, females consulted with higher frequency. There was a higher proportion of individuals with O blood type than in the normal population. Bleeding time was abnormal in 330 patients (56%). One hundred ten patients (19%) had won Willebrand disease and, among them, one third had a normal bleeding time. Isolated reduction of factor WII activity was found in 66 patients (11%, 51 males) and 32 of these had normal bleeding time. Eighty one patients (14%) were considered to have an hereditary platelet function defect. A precise diagnosis was not achieved in 332 patients (56%). CONCLUSIONS: Among patients consulting for mucocutaneous hemorrhages, 19% had von Willebrand disease, 11 had an isolated reduction of factor VIII activity, 14% had platelet function defects and in 56%, a precise diagnosis was not reached.

ABO Blood-Group System↗
PubMed1996

[Activated C protein resistance: laboratory study and prevalence of the defect in the Chilean population].

Activated protein C resistance (APCR) or Factor V Leiden has been recently described as the most prevalent hemostatic abnormality associated with venous thrombosis. In patients with familial thrombophilia, the prevalence of APCR is 19-60% and around 20% in sporadic venous thrombosis. APCR is usually measured by the degree of prolongation of Activated Partial Thromboplastin Time (APTT) on patient's plasma, induced by addition of APC in comparison to normal plasma. At the molecular level the defect is caused by a single-point mutation in the gene for factor V (FV) (G1.691-->A), that predicts the replacement of Arg506 by Glutamine. This mutation makes activated factor V resistant to inactivation by APC. Since the prevalence of the defect is highly variable among different populations, the objective of this work was to study its frequency in our population and in patients with thrombophilia. We defined the normal range for APTT ratio (APTT + APC/APTT - APC) in a group of 73 healthy volunteers in whom the presence of FV Q506 mutation was searched using Mull enzyme digestion of PCR amplified genomic fragment containing the nucleotide 1.691. The lower limit of APTT ratio established in this group was 2.13. APCR was found in 6 out of 159 control subjects (3.8%) and in 14/50 (28%) of patients with thrombosis. In 13 cases as a single defect and in one associated to type I protein C deficiency. All the APCR patients and control subjects were heterozygotes by gene analysis. The results demonstrate that in our population APCR is also the most common defect associated with thrombosis, in accordance with a high prevalence in the population. The ability to screen for this defect will permit the identification of carriers that would benefit of preventive therapy at risk situations.

Base Sequence↗
PubMed1996

[Hemophilia A: analysis of intron 18 and intron 7 of factor VIII gene and their role in a diagnostic strategy for carrier detection in a Chilean population].

Hemophilia A is an X-linked disorder of coagulation caused by a deficiency of factor VIII. A larger number of different mutations in the VIII gene have been identified. Thus, the detection of female carriers, depends upon the analysis of DNA polymorphisms in and near the factor VIII gene. Our aim was to develop a strategy, earlier reported, for carrier testing in families at risk of hemophilia A. In this study, we analyzed the DNA polymorphisms in 26 affected families, with use of the factor VIII intragenic polymorphisms identified by the restriction enzymes BclI and AlwNI, and by differential hybridization with sequence-specific oligonucleotide probes recognizing BclI and AlwNI polymorphism. While the DNA polymorphism detected by BcilI site in intron 18 of the factor VIII gene was informative for 38% families studied, the AlwNI/intron 7 polymorphism provided additional information (4%). The carrier status of the remaining 58% could be determined utilizing the other polymorphisms suggested by strategy. The two polymorphic sites used combined with the other polymorphisms, intragenic and extragenic, can generate levels of informativeness greater than 98%. We concluded that the strategy for carrier testing would be a good alternative in genetic counselling for hemophilia A, but its limitations must be carefully taken into account.

Chile↗
PubMed1995

Measurement of pleural fluid cholesterol and lactate dehydrogenase. A simple and accurate set of indicators for separating exudates from transudates.

OBJECTIVES: To evaluate the usefulness of diverse combinations of pleural cholesterol concentration, pleural or serum protein, and lactate dehydrogenase (LDH) levels for the differentiation of pleural exudates and transudates. DESIGN: Prospective laboratory study of pleural effusions. SETTING: Medical school hospital. PATIENTS: One hundred eighty consecutive internal medicine ward patients in whom the etiologic diagnosis of their pleural effusion was confirmed. MEASUREMENTS: Cholesterol concentration in pleural fluid and protein and LDH both in pleural fluid and blood serum. RESULTS: According to their etiology, 49 (27.2%) of the effusions were transudates and 131 (72.7%) were exudates. Using a cutoff point of 45 mg for pleural cholesterol and values for protein and LDH of Light et al, the best diagnostic power corresponded to the combination of pleural cholesterol and LDH: cholesterol level over 45 mg/dL and/or LDH over 200 IU/L identified exudates with a sensitivity of 99% and a specificity of 98%. All the other combinations showed inferior values and the criteria of Light et al reached 98 and 82%, respectively. CONCLUSIONS: The measurement of pleural cholesterol and LDH permits the separation of pleural exudates from transudates with an accuracy similar to the original report of Light et al, with the advantage of requiring only two laboratory determinations and no simultaneous blood sample.

Cholesterol↗
PubMed1993

[Diagnosis of von Willebrand's disease subtypes by the analysis of multimeric composition of plasma von Willebrand factor].

The accurate diagnosis of the type of von Willebrand's disease (vWD) is important for a better understanding of its pathogenesis and for adequate treatment decision. We assessed the usefulness of the analysis of the multimeric composition of von Willebrand factor (vWF) in the diagnosis of vWD variants. vWF is purified by gel filtration and polyclonal, heterologous antibodies are raised in rabbits, which are immunopurified and radioiodinated. These are used to reveal, by autoradiography, the bands of vWF of various molecular weights separated by electrophoresis in agarose gels. This procedure reveals that 74 (80%) out of 92 patients with vWD suffer the classic type (I) of the disease, 6 (6.5%) type as IIA, 6 (6.5%) as IIB and 6 (6.5%) as III. The test is necessary for the correct classification of the patients, but is complex, laborious and expensive; it should be performed in patients with high probability of vWD or after the generic diagnosis of vWD has been made.

Adolescent↗
PubMed1993

[HLA A, B, C and DR antigens in a urban population from Santiago of Chile].

HLA antigens vary in different ethnical groups and in Chile there are no reports on the frequency of these antigens in a normal representative population. The few existing studies are of indigenous populations and control groups, without including HLA-DR antigens. Therefore, the aim of this study was to study the frequency of HLA A, B and C antigens in 349 individuals and HLA-DR in 257, using the microlymphocytotoxicity method, and compared the results with those on normal caucasian populations (Europe and USA). Significant differences were found for 7 antigens of group A, 10 of group B, 4 of group C and 6 of group DR. The observed difference allow us to conclude that the population from Santiago has a distinct HLA antigen distribution. This fact must be bore in mind future studies in genetics, paternity or autoimmune diseases.

Adult↗
PubMed1993

[Evaluation of the determination of total cholesterol in Chilean clinical laboratories].

The precise and accurate measurement of total cholesterol is necessary to correctly identify hypercholesterolemia. The aim of this study was to assess the measurement of serum cholesterol in clinical laboratories using as acceptability criteria the recommendations of the "National Cholesterol Education Program" (that consider acceptable a deviation < 5% from the real value and ideal a deviation < or = 3%). In each of three assessments, three pools of lyophilized sera with different levels of cholesterol were used method. Twenty nine to 42.3% of laboratories had results within the ideal interval and 49.5 to 60% within the acceptable range of deviation. In the last assessment, only 17% of laboratories had their three values within the ideal range. Only 39.4% of laboratories use 200 mg/dl as the cut off point to diagnose hypercholesterolemia. It is concluded that the standardization of cholesterol measurement and the use of a common cut off point to diagnose hypercholesterolemia must be emphasized.

Chile↗
PubMed1992

Total sialic acid in human and canine platelets does not change with the platelet age.

Total platelet sialic acid (SA) was measured in three experimental conditions: (1) human and canine platelet density subpopulations obtained by centrifugation in arabinogalactan gradients, (2) circulating canine platelets during recovery from experimental immune and mechanical thrombocytopenias, and (3) platelets obtained from a patient with chronic immune thrombocytopenic purpura before and after splenectomy. The density of human and canine platelets is, in part, determined by their age. We found no significant differences in total SA between high-density (HD) and low-density (LD) platelets (9.32 +/- 2.0 vs. 9.55 +/- 1.3 micrograms/mg of platelet protein in dogs and 9.02 +/- 2.3 vs. 9.10 +/- 2.9 micrograms/mg in humans). In the human and canine thrombocytopenic models, the entrance of new platelets from the bone marrow is followed by their aging in the circulation. In these models, no significant changes in total SA content were detected in sequential measurements during the recovery of the thrombocytopenia. Accordingly, we conclude that total SA in human and canine platelets is unrelated to their age in circulation. These results do not support the notion that the loss of SA from membrane glycoproteins determines the recognition and removal of platelets from the circulation.

Animals↗
PubMed1990

[von Willebrand's disease].

von Willebrand's disease is the most frequent congenital disorder of primary hemostasis; it is transmitted in an autosomal manner and according to type there is an alteration in structure, function and/or synthesis or release of von Willebrand's factor. Patients present with muco-cutaneous hemorrhages of varying severity. Significant advances in the understanding of the molecular defect and laboratory diagnosis of the different subtypes of the disease have been made in the last years, but we still face the emergence of new subtypes and the difficulties posed by the genetic, clinical and laboratory variability of the disorder.

Humans↗