[Persistent elevation of aspartate aminotransferase (AST) due to the presence of macro-AST: Report of one case]. / Aumento aislado y sostenido de aspartato aminotransferasa por presencia de macroenzimas: Caso clínico.

We report an asymptomatic 23-year-old woman with an isolated and persistent increase in serum levels of aspartate aminotransferase (AST). An extensive work up including laboratory and image testing revealed no abnormalities thus suggesting the presence of macro-AST. A polyethylene glycol (PEG) precipitation assay was performed and confirmed the presence of macro-AST.

Aumento aislado y sostenido de aspartato aminotransferasa por presencia de macroenzimas: caso clínico / Persistent elevation of aspartate aminotransferase (AST) due to the presence of macro-AST: report of one case

We report an asymptomatic 23-year-old woman with an isolated and persistent increase in serum levels of aspartate aminotransferase (AST). An extensive work up including laboratory and image testing revealed no abnormalities thus suggesting the presence of macro-AST. A polyethylene glycol (PEG) precipitation assay was performed and confirmed the presence of macro-AST.

Insulinemia e índice HOMA en niños y adolescentes chilenos / Normal plasma insulin and HOMA values among chilean children and adolescents

Background: Plasma insulin and HOMA (homeostasis model assessment) index, used to determine insulin resistance, do not have local standard values for children and adolescents in Chile. Aim: To establish the normal reference intervals for insulin and HOMA in children and adolescents aged 10-15 years, according to sex and puberal maturation. Material and Methods: A cross-sectional study of 2,153 children and adolescents from Puente Alto County was performed, during 2009 and 2010. Anthropometry and self-report of puberal maturation were assessed. Fasting glucose (hexoquinase) and insulin blood levels (chemiluminiscence), were determined and HOMA index was calculated. Percentile distributions of these variables were calculated. Results: The reference group included only subjects with normal body mass index and fasting blood glucose (n = 1,192). Girls had higher insulin and HOMA values than boys (12.5 ± 6.0 and 9.1 ± 4.9 μϋ/mL (p < 0.01) and 2.7 ± 1.4 and 2.1 ± 1,1 (p < 0.01), respectively). Subjects with Tanner I and IIpuberal stages had lower insulin and HOMA mean values than subjects with Tanner III and IV (9.0 ± 4.3 and 12.5 ± 6.2μϋ/ml (p < 0.01) and2.0 ± 1 and2.8 ± 1.4 (p < 0.01), respectively). Conclusions: The 90th percentile of insulin and HOMA distributions according to sex and maturation, was selected as the upper cut-off point to identify individuals with insulin resistance. HOMA cutoff point for Tanner I and II boys was 3.2, for Tanner I and II girls was 4.1, for Tanner III and IV boys was 4.2 and for Tanner III and IV girls was 5.0.

[Normal plasma insulin and HOMA values among Chilean children and adolescents]. / Insulinemia e índice HOMA en niños y adolescentes chilenos.

BACKGROUND: Plasma insulin and HOMA (homeostasis model assessment) index, used to determine insulin resistance, do not have local standard values for children and adolescents in Chile. AIM: To establish the normal reference intervals for insulin and HOMA in children and adolescents aged 10-15 years, according to sex and puberal maturation. MATERIAL AND METHODS: A cross-sectional study of 2,153 children and adolescents from Puente Alto County was performed, during 2009 and 2010. Anthropometry and self-report of puberal maturation were assessed. Fasting glucose (hexoquinase) and insulin blood levels (chemiluminiscence), were determined and HOMA index was calculated. Percentile distributions of these variables were calculated. RESULTS: The reference group included only subjects with normal body mass index and fasting blood glucose (n = 1,192). Girls had higher insulin and HOMA values than boys (12.5 ± 6.0 and 9.1 ± 4.9 µÏ‹/mL (p < 0.01) and 2.7 ± 1.4 and 2.1 ± 1,1 (p < 0.01), respectively). Subjects with Tanner I and II pubertal stages had lower insulin and HOMA mean values than subjects with Tanner III and IV (9.0 ± 4.3 and 12.5 ± 6.2µÏ‹/ml (p < 0.01) and2.0 ± 1 and2.8 ± 1.4 (p < 0.01), respectively). CONCLUSIONS: The 90th percentile of insulin and HOMA distributions according to sex and maturation, was selected as the upper cut-off point to identify individuals with insulin resistance. HOMA cutoff point for Tanner I and II boys was 3.2, for Tanner I and II girls was 4.1, for Tanner III and IV boys was 4.2 and for Tanner III and IV girls was 5.0.

Diagnosis of mild platelet function disorders. Reliability and usefulness of light transmission platelet aggregation and serotonin secretion assays.

Light transmission platelet aggregation (PA), adapted to measure platelet secretion (PS), is the reference test for diagnosing platelet functional disorders (PFD). Problems with these assays include lack of standardisation, unknown reproducibility and lack of universally accepted diagnostic criteria. We addressed these issues in patients with inherited mucocutaneous bleeding (MCB). Normal and abnormal PA tests in 213 patients were reproducible in 93.3% and 90.4% of the cases, respectively. Mean intra-subject coefficient of variation for PA with strong agonists were <9% and mean intra-class correlation coefficient for weak agonists were >0.86 (P < 0.0001). Concomitant impaired PA with 10 micromol/l-adrenaline and 4 micromol/l-ADP was observed in 13.7% of the controls. This combination was not considered per se a criterion for PFD. PA with adrenaline > or = 42% or irreversible aggregation with 4 micromol/l ADP had 93% and 95% Negative Predictive Value for diagnosing PFD, respectively. PA defects were consistently associated with abnormal PS. In contrast, 14.3% of patients with MCB had isolated PS. Thus, standardized PA/PS assays are highly reproducible and concordant in normal and patient populations. Normal PA with adrenaline and low ADP concentration robustly predict a normal PA. Simultaneous PA/PS assays enable the diagnosis of isolated PS defects. This study confirmed that hereditary PA-PS defects are highly prevalent.

Procarboxypeptidase U (TAFI) and the Thr325Ile proCPU polymorphism in patients with hereditary mucocutaneous hemorrhages.

BACKGROUND: Patients with hereditary mucocutaneous bleeding are difficult to diagnose and many of them fulfill the category of bleeders of unknown cause (BUC). The pathogenic role of hyperfibrinolysis has received little attention, despite the successful use of antifibrinolytic drugs in treating many of these patients. Theoretically, decreased plasma procarboxypeptidase U (proCPU) levels or lower carboxypeptidase U (CPU) stability would result in higher fibrinolytic activity and bleeding tendency. METHODS: We analyzed plasma proCPU and the distribution of the Thr325Ile proCPU polymorphism in 193 patients with mucocutaneous bleeding of whom 116 were bleeders of unknown cause (BUC), and in 143 healthy, age and sex-matched controls. RESULTS: ProCPU concentration was higher in women than in men, increased with age, and was significantly correlated with clot lysis time, platelet count, APTT, and PT. However, proCPU levels were unexpectedly higher in patients than in controls (968+/-134 vs. 923+/-147 U/L, p=0.004). The allele distribution of the Thr325Ile proCPU polymorphism was similar in both groups, with a low percentage of homozygous Ile/Ile. CONCLUSIONS: Our results indicate that the proCPU system is not of major importance in the bleeding pathogenesis of these patients. The higher proCPU levels in the patients may even modestly counteract the bleeding tendency.

High prevalence of bleeders of unknown cause among patients with inherited mucocutaneous bleeding. A prospective study of 280 patients and 299 controls.

BACKGROUND AND OBJECTIVES: Mucocutaneous bleeding (MCB) is the main expression of inherited disorders of primary hemostasis. However, the relative prevalence of these disorders, their clinical differential diagnosis, and the proportion of patients with MCB of unknown cause (BUC) after an initial comprehensive laboratory testing are unknown. DESIGN AND METHODS: We studied prospectively 280 consecutive patients with MCB and 299 matched controls, using strict inclusion and exclusion criteria. A single physician recorded the clinical data in a bleeding score and estimated the severity of bleeding in clinical categories. Laboratory criteria for the diagnosis of von Willebrand's disease (VWD) and platelet function defects were established from reference values derived from controls. RESULTS: Fifty patients (17.9%) had VWD (type 1VWD=45, type 2=5). Platelet function defects and mild clotting factor deficiencies were found in 65 (23.2%) and 11 (3.9%) patients, respectively. Thirteen (11.5%) patients had combined defects. The remaining 167(59.6%) patients had BUC, with prolonged bleeding time in 18.6% as their only abnormality. All these disorders, including BUC, were clinically undistinguishable. Moreover, no relationship was found between the severity of bleeding and VWF/platelet function variables. INTERPRETATION AND CONCLUSIONS: The diagnostic efficacy of a first laboratory testing in patients with hereditary MCB is 40.4%. Most patients have a disease(s) of high prevalence but unknown pathogenesis. Concurrent bleeding disorders in the same patient are frequent. Our results support the proposal that low plasma VWF levels, but also platelet function defects, should be considered risk factors rather than unequivocal causes of hemorrhages.

Circulating platelet-derived microparticles in systemic lupus erythematosus. Association with increased thrombin generation and procoagulant state.

The risk for thrombosis is significantly increased in systemic lupus erythematosus (SLE), affecting both venous and arterial vessels. Activated platelets are known to participate in thrombus formation and growth. A general feature of activated cells is the shedding of microparticles (MP) which support coagulation by exposure of negatively charged phospholipids and possibly tissue factor (TF). In this work we characterized circulating MP in patients with SLE and their relationship with a procoagulant state. Thirty patients with SLE (aged 15-72 years, mean age 38 years) and 20 healthy controls (aged 22-54 years, mean age 34 years) were studied; patients fulfilled 4 revised criteria for SLE. The number and cellular source of circulating MP were determined by flow cytometry using double labeling with specific monoclonal antibodies and annexin V. Thrombin generation was measured as the endogenous thrombin potential (ETP) without the addition of exogenous phospholipids and TF; under these conditions the generation of thrombin depended directly on the number of MP present in plasma. Thrombin anti-thrombin (TAT) and plasmin-antiplasmin (PAP) complexes were measured by ELISA. Compared to the controls, circulating MP were significantly elevated in the patient group (1218 +/- 136 vs 653 +/- 74 x 10(3)/ml plasma, p: 0.0007). In both groups, most of these MP were of platelet origin (927 +/- 131 vs 517 +/- 72 x 10(3)/ml plasma, p:0.009 ). ETP was higher among patients as compared to the controls (804 +/- 64 vs 631 +/- 37 nM thrombin, p: 0.025). Plasma levels ofTAT in patients and controls were 3.4 +/- 0.8 and 1.4 +/- 0.5 microg/L, respectively (p:0.04), and of PAP complexes were 62.5 +/- 14 and 24.05 +/- 2.5 microg/ml, respectively (p: 0.014). The number of platelet-derived MP correlated significantly with thrombin generation (r: 0.42; p: 0.038) and TAT levels (r: 0.40; p: 0.035). We did not find an association of circulating MP with disease activity nor with the presence of antiphospholipid antibodies. The increased number of circulating platelet-derived microparticles and their association with high ETP and activation of the coagulation system suggest that these microparticles play an important role in the pathogenesis of the prothrombotic state in SLE patients.

Salmonella enterica serovar Typhi O:1,9,12 polysaccharide-protein conjugate as a diagnostic tool for typhoid fever.

Serologic tests play an important role in diagnosis of typhoid fever. In an effort to develop a more defined reagent for these tests, purified Salmonella enterica serovar Typhi (ST) O:1,9,12 polysaccharide was conjugated to human serum albumin (HSA), and the conjugate was purified chromatographically to yield a reagent with 2 moles ST O polysaccharide per mole HSA. In 40 patients with bacteriologically confirmed typhoid fever, significant dot immunobinding titers (> or =20,000) were present in 28 (70%) tested with 100 ng of ST O antigen-HSA (ST O-HSA) conjugate, in 38 (95%) tested with 100 ng of ST lipopolysaccharide, and in 16 (40%) tested with purified unconjugated ST O chains. In sera from 22 patients with other nontyphoid fevers, 2 (9.1%) had such reactivities with 100 ng of ST O-HSA, 1 (4.5%) had such reactivity with 100 ng of ST lipopolysaccharide (4.5%), and none reacted with 100 ng of unconjugated ST O chains. None of the 17 healthy-control sera reacted significantly with any of the ST reagents. None of the patient or control sera reacted with unconjugated HSA. The sensitivity of dot immunobinding for typhoid fever was 70% with 100 ng of ST O-HSA, somewhat lower than that with 100 ng of ST lipopolysaccharide (95%) but similar to that of the Widal H agglutination test with a > or =1/160 cutoff (74%). Specificities of these tests were 91%, 95%, and 86%, respectively. These preliminary results suggest that ST O polysaccharide-protein conjugates could provide a nontoxic, easily quality-controlled synthetic reagent for analysis of human immune responses to ST as well as for the development of new diagnostics and vaccines for typhoid fever.

Platelet membrane glycoprotein polymorphisms do not influence the clinical expressivity of von Willebrand disease type 1.

Von Willebrand disease (VWD) is characterized by a significant variation in bleeding symptoms among patients with similar laboratory profiles and equivalent plasma levels of von Willebrand factor (VWF) activities. Considering the recent suggestion that platelet membrane glycoprotein polymorphisms (PltGPs) may play a role as modulators of thromboembolic or haemorrhagic diseases, we investigated the role of different PltGPs and GPVI content in the clinical expression of patients with VWD type 1.The diagnosis of VWD (n = 76) was based on laboratory findings (VWF:Ag, VWF:RCo, VWF:CB, FVIII:C, and multimer analysis), family and personal history of bleeding. All patients were interviewed using a standardized questionnaire, and classified into two categories: bleeders (unequivocal bleeding tendency, n = 53) and non bleeders (absence of bleeding symptoms, n = 23). PltGPs, HPA-1, 2 and 5 and C807T of GPIa were determined by fluorophore-labelled hybridization probes on a LightCycler. GPVI content was measured by western blotting. VWF:Ag,VWF:RCo,VWF:CB and FVIII:C levels were not significantly different between symptomatic and asymptomatic patients. There were no differences in the genotype distribution and allele frequencies between bleeders and non bleeders for the platelet alloantigen systems HPA-1, 2, 5 and the GPIa C807T polymorphism. The levels of platelet GPVI were similar in symptomatic and asymptomatic VWD patients (109.6 +/- 58.4 vs 114.1 +/- 52.5, respectively; p: 0.77). These results show that PltGPs HPA-1, 2 and 5 or the C807T dimorphism of GPIa do not influence the clinical expressivity of VWD type 1. The wide variation in GPVI content was not associated with the severity of bleeding in the patients. Other genetic factors that may contribute to the variable expressivity of VWD type 1 should be investigated.

Thrombin generation in platelet-poor plasma is normal in patients with hereditary mucocutaneous haemorrhages.

Mild hereditary bleeding disorders presenting with mucocutaneous haemorrhages are usually difficult to diagnose. We measured thrombin generation in platelet-poor plasma (TG-PPP) in 206 patients with a clinically unequivocal bleeding tendency: 45 with von Willebrand disease (vWD), 49 with platelet aggregation/secretion defects (PASD), 10 with a combination of both and 102 who did not fit the diagnostic criteria for any known haemostatic disorder. TG-PPP was not significantly different from controls in all patient groups, indicating that an abnormality in the plasmatic clotting system is unlikely to contribute to the bleeding in patients with type 1 vWD and PASD. In patients with undiagnosed mild hereditary bleeding disorders, there must be other mechanisms which explain the abnormal haemorrhagic tendency, most likely as yet unrecognized defects in platelet-vessel wall interaction. As a next step we plan to investigate thrombin generation in PRP.