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Biomedical subjects

S Handler

Publications and source records attributed to S Handler.

At least 19 recordsLinked to original sources
PubMed1999

The Factor V (Leiden) test: evaluation of an assay based on dilute Russell Viper Venom Time for the detection of the Factor V Leiden mutation.

In the present study a new clotting assay for the detection of an increased resistance of coagulation factor V against degradation by activated protein C (Factor V Leiden mutation, FVLM) was evaluated. The Factor V (Leiden) Test (Gradipore, North Ryde NSW, Australia) is based on the dilute Russell Viper Venom Time (DRVVT), which is prolonged when the plasma sample is preincubated with dilute whole Agkistrodon contortrix contortrix venom for activation of protein C (PC). In contrast to the DRVVT based global assay, Protein C Pathway Test (Gradipore, North Ryde NSW, Australia) this new assay is expected to be more specific for FVLM because of optimized amounts of the venom. The test result is expressed as the ratio between the DRVVT with and without addition of the venom. The following precision values were found: intraassay coefficient of variation (CV): 5.53% (n=20) in the normal range, 4.30% (n=20) in the pathological range; interassay CV: 6.90% (n=10) and 7.64% (n=10), respectively. A normal range (5th to 95th percentile) of 2.12 to 3.08 was calculated from 50 healthy controls. A ratio below 2.12 was found in all samples from patients with FVLM (n=21), in 9 of 12 patients with PC, in 0 of 6 with protein S (PS), and in 0 of 4 with antithrombin (AT) deficiency. There was, however, a good discrimination between carriers of the FVLM (highest ratio 1.44) and patients deficient in PC (lowest ratio 1.59), in particular when samples were prediluted with factor V deficient plasma FVDP (1.16 vs. 1.96, respectively). Predilution of samples with FVDP caused a clear discrimination between controls and patients deficient in PC, PS, AT, and FVLM-positive individuals and also in patients on oral anticoagulant treatment. Our data show that the Factor V (Leiden) Test discriminates well between carriers of the FVLM and healthy controls or patients deficient in PC, PS, and AT. Individuals presenting values between the lower cutoff of controls and the range in which FVLM-positive individuals are found are highly suspicious for protein C deficiency.

Antithrombins↗
PubMed1999

Evaluation of the automated coagulation analyzer SYSMEX CA 6000.

In the present study the coagulation analyzer SYSMEX CA 6000 (TOA Medical Electronics Co., Kobe, Japan), an analyzer equipped with a photooptical clot detection unit and a cap-piercing system, was evaluated with respect to its technical characteristics in the determination of standard coagulation tests (prothrombin time, activated partial thromboplastin time, thrombin time, fibrinogen, and antithrombin) and in the determination of coagulation single factor activities. In the normal and in the pathological range the intraassay coefficients of variation (CV) and interassay CV for most parameters were below 5% (exceptions: intraassay CV 5.4% for prolonged thrombin time; intraassay CV 9.26% and interassay CV 10.7% for decreased antithrombin; interassay CV 5.62% for fibrinogen in the normal range, intraassay CV 10.1% for fibrinogen greater than 7.0 g/L; intraassay CV 6.36% and interassay CV 11.7% for decreased fibrinogen; interassay CV 11.6% for prolonged activated partial thromboplastin time; interassay CV 6.12% for decreased factor VII). Interference studies with lipemic, icteric, and hemolytic samples showed just minor influences of these abnormal sample characteristics on prothrombin time, activated partial thromboplastin time, fibrinogen, and antithrombin measurements when compared to the results obtained by using mechanical clot detection (STA, Stago Diagnostica, Asnieres-Sur-Seine, France). No carryover was detected in alternating measurements of heparinized (3 U/mL unfractionated heparin) and normal plasma samples. Measurement of the activities of clotting factors V, VII, VIII, and IX showed a good correlation (r=0.993 to r=0.977) between SYSMEX CA 6000 and STA. Our results demonstrate that using SYSMEX CA 6000 analyzer basal routine coagulation testing as well as specialized tests for single factor activities can be performed with satisfactory precision; in particular, the cap-piercing system has no negative effect on the performance of the analyzer.

Adult↗
PubMed1999

The green tea extract epigallocatechin gallate is able to reduce neutrophil transmigration through monolayers of endothelial cells.

Green tea is widely used in Asia and has also become popular in Western countries. The influence of green tea extracts on leukocytes is not well understood. Leukocytes play a crucial role in the process of inflammation. They migrate from the intravascular space into the tissue to attack micro-organisms. The aim of the current study was to investigate the influence of epigallocatechin gallate on leukocyte transmigration through endothelial cell monolayers and thereby evaluate its potential role in the inflammatory process. Human umbilical vein endothelial cells were cultured on microporous membranes to achieve a monolayer. Freshly isolated neutrophils from healthy subjects were measured with a migration assay. The amount of untreated neutrophils migrating through untreated endothelial cell monolayers was used as control and set as 100%. Neutrophils and/or endothelial cell monolayers were pre-treated with epigallocatechin gallate using relevant, as well as higher and lower concentrations. The relevant plasma concentration of epigallocatechin gallate was able to significantly inhibit neutrophil migration through endothelial cell monolayers (69 +/- 6.4% SD; p < 0.05 compared to control), when both cell types (leukocytes and endothelial cell monolayer) were treated. This is similar to the situation after resorption in-vivo. Treating either neutrophils or endothelial cell monolayers alone led to significant reductions in migratory response (only neutrophils treated: 86 +/- 8.1% SD, p < 0.05; only endothelial cell monolayers: 77 +/- 6.1%, p < 0.05). In conclusion, epigallocatechin gallate was identified as a potent inhibitor of leukocyte migration through endothelial cell monolayers. The treatment of both cell types showed an additive effect. Endothelial cells seem to be more affected than neutrophils. Further clinical investigations are necessary to understand the potential clinical consequences.

Catechin↗
PubMed1999

Dexamethasone inhibits leukocyte migration through endothelial cells towards smooth muscle cells.

Leukocyte interactions with endothelial cell monolayers (ECM) and smooth muscle cells (SMC) play an important role during inflammatory processes. Several studies describe an inhibitory effect of dexamethasone on polymorphonuclear leukocytes (PMNL), endothelial cell function, and interleukin-1 (IL-1) release. Aim of the current study was to investigate the influence of dexamethasone on leukocyte migration through an endothelial cell monolayer towards SMC-layers stimulated by tumor necrosis factor-alpha (TNF-alpha). Using a recently developed triple chamber migration system, SMC-layers were cultured on the bottom of a 24-well plate. On the upper surface of the first filter, ECM were cultured, the second filter was a collecting filter. The amount of leukocyte migration through ECM towards TNF-alpha-stimulated smooth muscle cell layers with and without dexamethasone-pretreatment was measured using a fluorescence technique. The pretreatment of SMC-layers with dexamethasone reduced the amount of leukocyte migration down to 92 +/- 8.8% (0.001 mM, p=n.s.), to 67 +/- 5.7% (0.01 mM, p<0.05), to 53 +/- 4.6% (0.1 mM, p<0.05), and to 41 +/- 5.0% (1 mM, p<0.05). In conclusion, dexamethasone treatment of smooth muscle cell layers inhibits leukocyte migration through ECM towards smooth muscle cell layers. The inhibition seems to be due to a decrease in IL-1 release. Treatment of all cell types, PMNL, endothelial cells, as well as smooth muscle cell layers, simulating an in-vivo situation, seems to have an additive effect.

Cell Culture Techniques↗
PubMed1999

Heparin lowers plasma levels of activated factor VII.

Based on heparin's antithrombin and anti-FXa activity and its in vitro inhibition of activated factor VII (FVIIa) activity, we hypothesized that unfractionated heparin (UFH) may decrease plasma levels of FVIIa in humans. Therefore, 10 healthy young male volunteers received an intravenous UFH infusion over 24 h. Heparin decreased FVIIa levels by 30% (95% CI 14-47%) at 12 h, which was sustained until 24 h. In contrast, neither the substrate pool (i.e. total factor VII) as measured by FVII antigen nor FVII activity were affected by UFH. These results may improve our understanding of the regulation of FVIIa levels and heparin's mode of action.

Adult↗
PubMed1999

The Philadelphia story: the 22q11.2 deletion: report on 250 patients.

A submicroscopic deletion of chromosome 22q11.2 has been identified in the majority of patients with the DiGeorge, velocardiofacial, and conotruncal anomaly face syndromes, and in some patients with the Opitz G/BBB and Cayler cardiofacial syndromes. We have been involved in the analysis of DiGeorge syndrome and related diagnoses since 1982 and have evaluated a large number of patients with the deletion. We describe our cohort of 250 patients whose clinical findings help to define the extremely variable phenotype associated with the 22q11.2 deletion and may assist clinicians in providing genetic counseling and guidelines for clinical management based on these findings.

Abnormalities, Multiple↗
PubMed1997

Evaluation of a new screening assay ProC Global for identification of defects in the protein C/protein S anticoagulant pathway.

In the present study a new assay, ProC Global, globally estimating the activity of the main plasma components of anticoagulant protein C/protein S pathway, was evaluated with respect to test characteristics and its sensitivity in the detection of deficiency states of protein C and protein S and of increased aPCR. In the ProC Global assay procedure protein C is activated in patient's plasma by an activator reagent (venom from agkistrodon contortrix). The extent of the prolongation of a sample's aPTT, caused by the activation of protein C, is taken as a measure for its anticoagulant capacity. Ninety-eight patients with one of the above mentioned defects were investigated. Decreased plasma protein C activity and increased aPCR were detected with a sensitivity of 1.0, while only 11 of 14 patients with decreased levels of free protein S antigen showed abnormal results in the ProC Global assay (sensitivity = 0.79). The test can be used in heparinized samples up to 1.0 anti Xa U/ml heparin (UFH and LMWH). When samples from patients on oral anticoagulant treatment are prediluted with factor V deficient plasma the test is sensitive for increased aPCR.

Administration, Oral↗
PubMed1997

Evaluation of bedside prothrombin time and activated partial thromboplastin time measurement by coagulation analyzer CoaguCheck Plus in various clinical settings.

In the present study CoaguCheck Plus (CCP), a coagulation test system using whole blood, was evaluated with respect to its comparability with widely distributed conventional routine coagulation assays. A correlation of r = 0.997 (p < 0.0001) was found between INR of CCP-prothrombin time (CCP-PT) and Thrombotest (KC-1 analyzer) in patients on oral anticoagulant therapy. A correlation of r = 0.899 (p < 0.001) between CCP-aPTT and Actin ES aPTT (STA analyzer) was found in heparinized patients. Impaired hepatic hepatic coagulation factor synthesis in liver cirrhosis patients was detected by CCP-PT with a sensitivity of 0.75 and by Normotest (STA analyzer) with a sensitivity of 0.92. Those patients with normal CCP-PT values and liver disease had, only mild reductions (> 30% of normals) in coagulation factors II, V, VII or X. CCP-aPTT was also performed in patients with a deficiency in the so called endogenous coagulation factors VIII, IX, XI and XII. CCP-aPTT showed a sensitivity similar to that of Actin FS aPTT in the detection even of mild deficiencies in factors VIII, IX and XII; factor XI deficiency was however detected only in patients with severe (< 12% of normals) disease; lupus anticoagulants were detected with a high sensitivity.

Blood Coagulation Tests↗
PubMed1997

Morning hypercoagulability and hypofibrinolysis. Diurnal variations in circulating activated factor VII, prothrombin fragment F1+2, and plasmin-plasmin inhibitor complex.

BACKGROUND: Diurnal fluctuations of blood coagulation and fibrinolysis activity are thought to play a role in the observed circadian variation in the frequency of onset of acute cardiovascular events. In the present study, the diurnal variations in blood coagulation and fibrinolysis activity were investigated in 10 young, healthy control subjects by use of specific molecular activation markers. METHODS AND RESULTS: The plasma levels of activated factor FVII (FVIIa), the active portion of the main coagulation activator, decreased during the day (8 AM: 2.03 ng/mL, CI 1.16 to 2.88 ng/mL; 8 PM: 1.16 ng/mL, CI 0.81 to 1.5 ng/mL; P = .005), whereas FVII antigen did not change significantly. In parallel with the diurnal variations of FVIIa, we found a decrease of prothrombin fragment F1+2 (8 AM: 0.97 nmol/L, CI 0.79 to 1.15 nmol/L; 8 PM: 0.78 nmol/L, CI 0.64 to 0.93 nmol/L; P = .005), a molecular marker of intravasal thrombin generation. Evidence for a possible functional relevance of circulating FVIIa was found because this parameter was significantly correlated with prothrombin fragment F1+2 in 72 fasting healthy individuals (r = .29, P = .011). Plasminogen activator inhibitor-1 levels decreased (8 AM: 9.9 ng/mL, CI 7.7 to 12.1 ng/mL; 8 PM: 5.4 ng/mL, CI 3.8 to 6.9 ng/mL; P < .005), whereas plasmin-plasmin inhibitor complex levels, representing the degree of intravascular plasmin generation, concomitantly increased (8 AM: 235 micrograms/L, CI 198 to 272 micrograms/L; 8 PM: 449 micrograms/L, CI 391 to 507 micrograms/L; P = .008). CONCLUSIONS: Our data suggest that the diurnal changes in the plasma levels of activators and inhibitors of coagulation and fibrinolysis lead to corresponding changes in the activity state of these systems, leading to morning hypercoagulability and hypofibrinolysis.

Adult↗
PubMed1996

Improved characteristics of aPC-resistance assay: Coatest aPC resistance by predilution of samples with factor V deficient plasma.

Screening for a resistance against activated protein C (aPCR), which is in most cases caused by FV:Q506 mutation, is performed by functional tests measuring the effect of aPC on activated partial thromboplastin time (aPTT). Because of an insufficient discrimination between FV:Q506 mutation negative and positive individuals with the first generation of the functional test Coatest aPC Resistance (Chromogenix AB, Mölndal, Sweden), the definition of an arbitrary cut-off level was only possible using the results of DNA analysis. The use of an arbitrary cut-off level still resulted in unsatisfactory low sensitivity and specificity for the functional test. Thus, time- and cost-consuming DNA analyses had to be performed frequently to establish the diagnosis. The objective of this study was to evaluate an improved version of this assay that uses predilution of samples with factor V deficient plasma containing a heparin neutralizer. Using the data from 32 FV:Q506 mutation positive and 55 mutation negative individuals, the authors calculated a cut-off value resulting in an enhanced sensitivity (0.91 versus 1.0) and specificity (0.77 versus 1.0) compared to the old one. Imprecision was lowered from 5.36% (first generation) to 2.43%, in particular in samples with longer clotting times. In patients with prolonged aPTT, either caused by therapy with oral anticoagulants or heparin, correct results were obtained with the second generation assay, in contrast to the first generation assay. With this second generation assay the number of DNA analyses can be substantially reduced.

Adult↗
PubMed1996

Increased levels of activated factor VII and decreased plasma protein S activity and circulating thrombomodulin during use of oral contraceptives.

In the present study the effect of oral contraceptive (OC) treatment on selected factors involved in the activation, i.e. circulating activated factor VII (cFVIIa), and in the inhibition of blood coagulation, i.e. plasma protein S activity and circulating thrombomodulin (cTM), were for the first time measured in OC users in a prospective study. Beside other coagulation variables, these parameters were measured during treatment with three low estrogen formulations containing different gestagen components (norgestimate, gestodene). During OC treatment increases in the activation markers prothrombin fragment F1 + 2 and D-Dimer were found, suggesting an increased activation of blood coagulation and fibrinolysis. Along with elevated plasma levels of FVII antigen, cFVIIa was also found increased in all three treatment groups, while inhibitory components of blood coagulation, plasma protein S activity and cTM, significantly and similarly decreased during treatment in all three treatment groups. We conclude that low dose estrogen pills induce similar changes in the plasma levels of main regulatory components of blood coagulation, despite differences in their gestagen components. Increased levels of activators and decreased activities of inhibitors may contribute to arterial and venous thrombotic complications seen in predisposed OC users.

Adult↗
PubMed1995

MR in neurofibromatosis of the larynx.

We report the MR results of four patients with plexiform neurofibromas of the larynx. Three had irregular margins and were circumferential around the airway. The distinction between regularly and irregularly shaped neurofibromas may have implications for symptom onset.

Biopsy↗