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Biomedical subjects

A Tripodi

Publications and source records attributed to A Tripodi.

At least 145 records · Page 8Linked to original sources
PubMed1986

Factor VIII activity as measured by an amidolytic assay compared with a one-stage clotting assay.

Factor VIII amidolytic activity was measured by a commercially available method and compared with clotting activity measured in a one-stage assay. Parallel assays with both methods were used for plasma samples from 40 blood donors with normal or high Factor VIII levels, 22 patients with hemophilia before or after treatment with Factor VIII concentrates, 10 patients with chronic liver disease, and 10 normal subjects with high Factor VIII levels after treatment with desmopressin. The results obtained with the amidolytic assay were highly correlated (r = 0.97) with those obtained in the one-stage clotting assay. There were no significant differences in the results with the two methods in any of the patient groups, although in two cases of mild hemophilia the amidolytic assay gave lower values than the clotting assay. The reproducibility of the amidolytic assay (coefficient of variation = 6%) was better than that of the clotting assay (12%) at both normal and low levels of Factor VIII.

Adult↗
PubMed1985

Assessment of a new instrument (Coag-A-Mate X2) for performing global clotting tests and specific factor assays.

Coag-A-Mate X2 (General Diagnostics) is an automated photo-optical system for detection of clots, which can be used for measuring prothrombin time (PT) and activated partial thromboplastin time (APTT) and assaying coagulation factors. We have compared results obtained with this instrument with those obtained by the manual method used routinely in our specialized laboratory. The instrumental results showed good precision (PT: between-assay CV from 1.3 to 3.0, APTT: from 2.2 to 3.1), and high degree of correlation with the manual results (for PT r = 0.99, for APTT r = 0.95). There was also good correlation between the two methods (0.98-0.99) for factor assays (V, VII, VIII, IX, X, XI, and XII). High output, reproducibility, comparability and flexibility make this instrument suitable for both clinical and research laboratories.

Autoanalysis↗
PubMed1985

Antithrombin Milano: a new variant with monomeric and dimeric inactive antithrombin III.

A qualitative defect of antithrombin III (AT III) has been demonstrated over three generations in eight members of an Italian family by the discrepancy between a normal amount of antigen and decreased antithrombin and anti-Xa activity in the presence or in the absence of heparin. By two-dimensional immunoelectrophoresis in the absence of heparin, two peaks of AT III were present in all patients' plasma. AT III was purified from normal and propositus plasma by sulfate dextran precipitation followed by heparin affinity chromatography. The elution profile of the patient's AT III was abnormal and allowed the separation of two populations of AT III, normal and abnormal. The first fraction (normal AT III) contained AT III activity, migrated as a single peak by two-dimensional immunoelectrophoresis and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), demonstrated a single band with a molecular weight (mol wt) identical to that of normal AT III (60,000). Conversely, the last fraction, devoid of AT III activity, migrated as a single abnormal peak by two-dimensional immunoelectrophoresis in the absence of heparin. By SDS-PAGE, two bands were observed: one with a mol wt of 60,000 and a second one with a mol wt of 120,000. Western blots clearly demonstrated cross-reactivity of the 120,000 and 60,000 mol wt bands with monospecific antisera to human AT III. Reduction of the 120,000 mol wt band converted it to a single 60,000 mol wt band, suggesting the presence of an abnormal dimeric form of AT III. The name AT III Milano is proposed for this new variant.

Adult↗
PubMed1985

[The role of erythrocyte deformability in the prolonged bleeding time in liver disease patients].

Hematocrit (Ht), red cell deformability (RCD) determined using a filtration method and bleeding time (BT) have been studied in 28 patients with severe chronic liver disease. Our results show a decrease of Ht (p less than 0.001), RCD (p less than 0.05) and a prolongation of BT (p less than 0.001) not related to the platelet count. Moreover, inverse relationships between Ht and BT (r = -0.52; p less than 0.01) and between RCD and BT (r = -0.54; p less than 0.01) have been found. We conclude that hemorheological alterations, such as decreased Ht and RCD, play an important role in primary hemostasis of patients with chronic liver disease.

Adult↗
PubMed1984

Clinical evaluation of a fully automated chromogenic method for prothrombin time compared with a conventional coagulation method.

The clinical usefulness of a chromogenic method for prothrombin time (PT) determination has been assessed in a wide range of clinical conditions, and it is compared with the conventional clotting method for PT. The new method appears to be as sensitive as the clotting PT to deficiencies of clotting factors of the extrinsic and common pathway, except for fibrinogen. Patients with proven liver disease were correctly diagnosed with a prevalence of abnormal results comparable to that by the clotting PT. Results by the two methods correlated highly (r = 0.96) for normal and congenitally deficient plasmas as well as for plasmas from patients on oral anticoagulant treatment (r = 0.95). High reproducibility (between-assay CV less than 3%) and easy adaptation to centrifugal analyzers make it a suitable candidate to replace the conventional method.

Adolescent↗
PubMed1982

Treatment of congenital antithrombin III deficiency with concentrates.

Antithrombin III concentrates were administered to a patient with hereditary AT III deficiency undergoing orthopaedic surgery. The plasma AT III level (heparin cofactor activity) was maintained at values in excess of 100% postoperatively. A mean dose of 0.74 u/kg (range 0.64 - 0.83) of AT III resulted in a 1% increase in AT III level after concentrate infusion. The half-life of AT III (mean 66 h; range 58-76) was shorter during surgery and in the early postoperative period suggesting an increased consumption of the inhibitor. At III antigen was consistently higher than heparin cofactor activity during the first 24 h after concentrate infusions. This discrepancy was associated with the presence in the patient's plasma of an AT III fraction showing a slower mobility than the main AT III peak on two-dimensional immunoelectrophoresis in the presence of heparin. A biological assay is preferred to an immunological assay in monitoring replacement therapy with AT III concentrates.

Adult↗
PubMedDate not supplied

A survey of inherited thrombotic syndromes in Italy. ad hoc Study Group.

A collaborative survey was conducted among Italian thrombosis centers to gather information about the number and clinical features of patients with inherited thrombotic syndromes. The survey, based on 74 unrelated kindreds, revealed that antithrombin III, protein C and protein S defects are the most frequent genetic disorders. Venous thromboembolism was more frequent than arterial thrombosis, which was seen in only a minority of cases, most frequently with dysfibrinogenemia. About half of the patients developed venous thrombosis with a similar incidence in antithrombin III, protein S and protein C defects. About half of the symptomatic patients had recurrences and 40% developed thrombosis after a triggering factor, most frequently after surgery, during the puerperium, pregnancy, oral contraceptive intake or bed rest. Deep venous thrombosis prevailed and superficial thrombophlebitis was rare in antithrombin III-deficient patients, whereas deep venous thrombosis was present in about half and superficial thrombophlebitis in about one third of the cases with protein S and protein C defects. The probability to be free of thrombosis decreases with increasing age and at 35 years can be estimated to be 47% both for men and women. There is, however, a group of patients who are still free of thrombosis despite their older ages.

Adolescent↗
PubMedDate not supplied

Screening for congenital coagulation disorders.

A thorough screening procedure to diagnose congenital coagulation disorders must start from a careful collection of the personal and family clinical history, followed by a two-step laboratory screening. The first step is aimed at detecting the most frequent and well established causes of hemorrhage by a simple battery of laboratory tests such as bleeding time, platelet count, prothrombin time and activated partial thromboplastin time. The second step is to be performed in case of a past history of bleeding, but normal first-step laboratory screening and is aimed at detecting the less frequent abnormalities of hemostasis such as factor XIII, antiplasmin, platelet factor 3, von Willebrand factor, tissue plasminogen activator and dysfibrinogenemia, to which the first-step screening tests are not sensitive.

Bleeding Time↗
PubMedDate not supplied

Chromogenic substrates for activated partial thromboplastin time testing: are they worth using?

In hemostasis testing the development of chromogenic substrates provides an alternative to the traditional methods based on the detection of forming clots. The new technology has often replaced the clotting tests, especially in the area of single clotting factor and inhibitor assay, less frequently for global screening tests. We report studies of the validity and clinical application of two reagents for activated partial thromboplastin time (APTT) testing with chromogenic substrates in comparison with the conventional clotting method. Congenital deficiencies of the intrinsic coagulation pathway, other than hypo- and dysfibrinogenemia detected by chromogenic APTT, agreed with those detected by the clotting APTT. The results with the two methods for plasma under heparin treatment suggest a lesser responsiveness of the chromogenic methods to heparinization. The chromogenic methods demonstrated the presence of the lupus anticoagulant in the majority of tested samples of known lupus subjects, but with a lower responsiveness than the clotting method. In conclusion, we found chromogenic APTT suitable for hemostasis testing because it generally gives the same information as the conventional clotting method with the exception of heparin monitoring and lupus anticoagulant detection, where an improved sensitivity would be desirable.

Blood Coagulation Disorders↗
PubMedDate not supplied

Elevation of thrombin-antithrombin complexes during thrombolytic therapy in patients with myocardial infarction.

In patients with acute myocardial infarction (AMI) treated with streptokinase (SK) or recombinant tissue-type plasminogen activator (rtPA) we found high levels of thrombin-antithrombin (TAT) complexes signalling a significant activation of the coagulation cascade. In the SK-treated group the median pretreatment TAT complexes levels were 5.0 micrograms/l and in all patients, whatever the pretreatment level, TAT complexes increased following treatment. A statistically significant increase (medians = 20.3 and 12.0 micrograms/l) was observed 90 and 180 min after starting SK. The mean pretreatment level in the rtPA-treated group was also 5.0 micrograms/l and in all but one patients TAT complexes increased following treatment. A statistically significant increase (medians = 37.0 and 30.5 micrograms/l) was observed 90 and 180 min after starting rtPA. There was no statistically significant difference between TAT complexes in the two groups of patients either before or 90 min after treatment, whereas at 180 min the median concentration of TAT complexes was significantly higher for rtPA- than for SK-treated patients. We did not find an association between coronary vessels patency after thrombolysis and concentrations of TAT complexes; however, the rate of occluded vessels was very low (4 out of 30 patients), so that a difference was perhaps lost due to the insufficient size of the sample. In conclusion, we found thrombin activity during thrombolytic therapy in patients with AMI. There is no important difference in this respect between rtPA and SK. Whether or not this phenomenon is responsible for early rethrombosis remains to be explored by larger studies.

Antithrombins↗
PubMedDate not supplied

A chromogenic assay of prothrombin compared with coagulation tests during anticoagulant therapy and liver disease.

A standardized chromogenic assay of prothrombin (factor II, FII) was compared with a conventional coagulation assay and global tests (Quick prothrombin time, Hepatoquick) in patients on oral anticoagulant therapy. Twenty patients with chronic liver disease were also investigated. Studies of precision showed a coefficient of variation ranging between 2.9 and 4.1% in both normal and anticoagulant samples. Accuracy and variability studies yielded satisfactory results. There was a highly significant positive correlation between chromogenic and coagulation assays, whereas correlation with global coagulation tests was much lower, particularly when normal plasmas were tested. In patients with liver disease, FII assay gave reduced values and appeared at least as sensitive as global coagulation tests in showing the synthetic defect occurring in liver disease. These findings suggest that the chromogenic assay can be employed in the clinical laboratory, even though prospective studies are warranted to establish its predictive value.

Anilides↗
PubMedDate not supplied

Treatment with stanozolol of type I protein C deficiency in an Italian family.

Functional and immunological assays specific for protein C were employed in the study of a family with congenital protein C deficiency associated with venous thromboembolism. By both assays, four members of the family belonging to two generations had half-normal PC levels. These findings, as well as the normal mobility of the protein in crossed immunoelectrophoresis, suggest that PC deficiency in this family is due to the decreased synthesis of a functionally normal protein. In one member of the family oral administration of the anabolic steroid stanozolol increased PC levels until normal values, suggesting that the defect can be overcome by pharmacological stimulation of protein synthesis.

Adult↗
PubMedDate not supplied

Inherited deficiency of antithrombin III in an Italian kindred.

Life-long symptoms of venous thromboembolism were present throughout five generations in a large Italian kindred. Eight out of the 22 tested members of the family had reduced plasma levels of antithrombin III (AT III), the main physiological inhibitor of blood coagulation. Three of them, aged 2-28 years, but no thrombotic manifestations. AT III deficiency, which was hitherto thought to be very rare in this country, appeared to be related to a reduced synthesis of the protein without any qualitative abnormality. This view is supported by the concomitant reduction of AT III levels as demonstrated by biological and immunological assays, as well as by a normal pattern of the protein in double-crossed immunoelectrophoresis with and without heparin added to the agarose gel. Long-term treatment with oral anticoagulants appeared to prevent further thromboembolic episodes in two patients, even though plasma AT III levels remained unchanged.

Adolescent↗
PubMedDate not supplied

An improved method for measuring red blood cell filterability.

A new simple method for measuring red blood cell (RBC) filterability by weighing the amount of RBC filtered through micropore membranes is described. Red cell filterability by weighing (RCFW) is determined on washed RBC resuspended in phosphate-buffered saline (PBS) at low (5%) hematocrit. The filtration step is performed using gravity alone and the amount of the filtered suspension is referred to the filtration of PBS alone through the same membrane. The new method shows a reproducibility better than that of the widely used Dormandy technique, with a lower coefficient of variation (5.3 vs. 7.2%) and a higher sensitivity to artificially hardened RBC.

Blood Viscosity↗