Biomedical subjects

M I Bokarewa

Publications and source records attributed to M I Bokarewa.

13 recordsLinked to original sources

PubMed2002

Intra-articular tissue factor/factor VII complex induces chronic arthritis.

OBJECTIVE: Fibrin accumulation in the joint cavity is a common feature of chronic arthritides, such as rheumatoid arthritis (RA). Complex formation between tissue factor (TF) and factor VII (FVII) is the initial step in such a fibrin formation. METHODS: To assess the role of the TF/FVII complex in the pathogenesis of joint inflammation, 1) the levels of TF/FVII complex were measured in synovial fluid of RA patients; 2) the complex was injected to healthy mice intra-articularly. RESULTS: Morphological analysis of the joints 4 days after TF/FVII injection revealed influx of CD4-Mac1+ mononuclear leukocytes into synovial tissue followed by cartilage and bone destruction. Inflammation induced by TF/FVII complex was more profound than that caused by each of the proteins separately, both with respect to frequency, severity and duration of arthritis. Interaction between macrophages and lymphocytes in sustaining joint inflammation was proved by the requirement of the combined lymphocyte/ monocyte depletion to abolish TF/FVII induced arthritis. Induction of monocyte attracting chemokines (MIP-1 alpha and RANTES) was shown to be one of the potential mechanisms for TF/FVII complex triggered inflammatory cell influx. Interestingly, TF/FVII complexes were detected in synovial fluid of 20/40 patients with RA. CONCLUSIONS: Altogether these findings indicate that TF/FVII complexes, frequently found intra-articularly in joints of RA patients, may be an important component in both induction and progression of chronic destructive arthritis.

Animals↗

PubMed2001

Thrombin generation and mortality during Staphylococcus aureus sepsis.

Sepsis-induced abnormalities of coagulation may contribute to mortality during severe bacterial infection. The aim of this study was to examine changes in coagulation parameters and to assess the role of protein C supplementation during murine S. aureus sepsis. Gram-positive sepsis was characterized by a hypercoagulable state with predominant activation of the external coagulation pathway, registered as an early increase of tissue factor activity and concomitant reduction in protein C. The internal coagulation pathway was unaffected. No correlation between the changes of coagulation parameters and the intensity of inflammation, determined as serum IL-6 levels, was found. Supplementation with neither protein C or APC favoured survival in S. aureus sepsis. Reduction in thrombin generation in response to protein C supplementation was associated with significantly increased survival.

Animals↗

PubMed2000

Response to activated protein C during normal menstrual cycle and ovarian stimulation.

Oestrogen has been pointed out as a pre-thrombotic factor. Protein C is a key enzyme in the down-regulation of blood coagulation. Recent data suggest that activated protein C (APC) resistance which is not due to the factor V:Q 506 Leiden mutation and appears to be acquired, is also a risk factor for thrombosis. In this study, we evaluated the endogenous oestradiol production and its possible influence on APC. Eighteen normally menstruating women were studied during one ovulatory cycle. Furthermore, 20 women undergoing controlled ovarian stimulation, and achieving extremely high oestradiol concentrations, were investigated. Normalized APC (nAPC) ratio (clotting time of tested sample/clotting time of pooled control plasma) was measured. Samples collected on menstrual cycle days 1-3, 6-8, 13-14, 20-24 corresponded to nAPC ratios 1.02 +/- 0.19 (mean +/- SD), 1.05 +/- 0. 15, 1.02 +/- 0.16 and 1.03 +/- 0.21 respectively. During ovarian stimulation, the nAPC ratios were 0.99 +/- 0.12, 1.03 +/- 0.18, 1.01 +/- 0.16 and 0.97 +/- 0.13 at oestradiol minimum, days 5-8 pre-oocyte retrieval, oestradiol maximum and at oocyte retrieval respectively. In spite of the great difference in the concentrations of oestradiol between women in normal menstrual cycle and women undergoing ovarian stimulation, no difference in nAPC ratios was observed.

Adult↗

PubMed1998

Reactivity against phospholipids during pregnancy.

Antibodies against phospholipids (PLa) are often thought to be associated with the development of activated protein C (APC) resistance. In the present study, PLa were followed throughout 29 healthy pregnancies and compared to APC resistance. The level of PLa did not change during pregnancy [6.9 +/- 3.7 GPL week 12 versus 6.3 +/- 2.8 GPL week 37; 3.3 +/- 1.8 MPL versus 3.2 +/- 1.5 MPL; and lupus anticoagulant (LA) coefficient 0.99 +/- 0.11 versus 0.94 +/- 0.09], in contrast to the APC resistance, which was suppressed (0.96 +/- 0.22 versus 0.78 +/- 0.13, P < 0.05), but both parameters elevated after delivery (up to 8.7 +/- 4.2 GPL; 1.13 +/- 0.1 LA coefficient; 1.11 +/- 0.22 nAPC ratio; P < 0.05). Three women possessed PLa (1 CLa IgG +/- IgM; 1 IgG CLa +/- PSa +/- PEa; 1 PSa), no LA activity was registered. In the PLa-positive women, dynamics of the nAPC ratio during pregnancy was not related to PLa.

Activated Protein C Resistance↗

PubMed1998

Production of phospholipid antibodies in selected thrombophilic women differing in genotype at the 506 site of factor V.

The composition of antibodies against phospholipids (PLa) was analysed in 54 PLa-positive thrombophilic women, different in the factor V genotype (Arg506-Gln mutation carriers, n=23; and noncarriers, n=31). The presence of antibodies against prothrombin was also studied. The incidence of cardiolipin antibodies (CLa) and lupus anticoagulant (LA) activity was similar among the carriers and noncarriers, while phosphatidylserine antibodies (PSa) were often the only PLa detected in the carriers of the mutation (7/23 vs. 2/31; chi2=5.47, p<0.05). Antibodies against prothrombin were found in 11 of 54 patients. They segregated with PSa (8/19 vs. 3/35; chi2=8.54, p<0.025), but were equally distributed between carriers and noncarriers. The analysis of nAPC-ratio in patients with different PLa showed that it was consistently lower in the mutation carriers in whom none of the PLa caused further suppression. The noncarrier group positive for LA in several assays was associated with a reduction of nAPC-ratio (0.82+/-0.25 vs. 1.12+/-0.22, p<0.05). Our findings indicate that PLa contributing to the development of APC resistance are restricted to those possessing LA activity.

Adult↗

PubMed1997

Search for mutations in the genes for coagulation factors V and VIII with a possible predisposition to activated protein C resistance.

A total of 74 non-pregnant women with a previous episode of thrombosis were investigated for activated protein C (APC) resistance in the aPTT-based and factor IXa-X-based assays and for the presence of mutations in all APC-cleavage sites in the heavy chains of factor V and factor VIII. DNA fragments were amplified with the polymerase chain reaction (PCR) and those encoding for the Arg-306 and Arg-506 (factor V) and for Arg-740 (factor VIII) cleavage sites were subjected to restriction enzyme analysis. DNA fragments of 29 selected patients corresponding to the Arg-306 and Arg-679 cleavage sites in factor V, and to the Arg-336 and Arg-562 cleavage sites in factor VIII were sequenced. APC resistance was found in 40 cases, using the aPTT-based assay and in 35, using the factor IXa-X-based assay (23 patients were APC resistant in both assays), whereas 22 individuals had a normal response to APC. Forty-three patients carried Arg-506 to Gln mutation in factor V. No other polymorphism or mutation was found in the genes for factors V or VIII in the vicinity of the APC cleavage sites. It was concluded that the difference in response to APC in the two assays may not be explained by the presence of mutations in the APC cleavage sites of factor V and factor VIII in this group of patients. The data do not exclude the presence of mutations elsewhere in the factor V or factor VIII genes.

Adult↗

PubMed1997

Variability of the response to activated protein C during normal pregnancy.

The response to activated protein C (APC) was investigated in 28 healthy women, non-carriers of the Arg506-Gln mutation in factor V, throughout pregnancy (gestation weeks 12, 20, 28, 32 and 37) and after the delivery. A suppression of APC response was observed which reached lowest values by week 28 (nAPC-ratio 0.78 +/- 0.13), sustained low up to the end of pregnancy and rose after delivery (1.11 +/- 0.22; P < 0.05). APC resistance (nAPC ratio < 0.75) was registered in 16 of the 28 women (57%). A reduction of APC ratio was directly related to its value in the non-pregnant state, being most pronounced in the women with the highest APC ratio. Factor VIII increased during pregnancy and correlated inversely to APC ratio (Z coefficient = -0.645, P < 0.0001). The correlation became weaker in the course of pregnancy, losing significance by week 32. This was explained by the differences in profiles of the two variables: the lowest measured APC ratio preceded the peak of factor VIII in most cases. The most pronounced rise of factor VIII was found in the women with minimal levels of APC ratio between 0.8 and 0.7. These results allowed us to speculate that APC response is closely regulated during pregnancy, aiming to maintain a certain relevant level. Transitory reduction of APC response is connected to factor VIII and discussed as a prevalent mechanism of functional APC resistance during pregnancy.

Adult↗

PubMed1997

Combination of activated protein C resistance and antibodies to phospholipids in the development of thrombosis.

An insufficient response to activated protein C (APC) resistance and antibodies against phospholipids (PLa) are frequent laboratory findings associated with thrombosis. Studies investigating the coexistance of these two factors in thrombophilic patients and in patients with autoimmune disorders are summarized. The investigation of thrombophilic patients has revealed PLa in 35%. About half of these patients had a combination of PLa and APC resistance proved by the Arg506-Gln mutation in factor V (FV). A combination of APC resistance with PLa in this group of patients did not increase the risk of thrombosis recurrence. In the PLa-positive patients with autoimmune disorders having thrombosis in 10% to 56%, the incidence of the Arg506-Gln mutation in FV was significantly lower and varied between 2% and 9%. A known ability of PLa to induce APC resistance experimentally was often a reason to avoid the determination of APC response in PLa-positive patients. We suggest that PLa may play a dual role in the development of thrombosis in the carriers of the Arg506-Gln mutation in FV. On the one hand, PLas favor thrombosis by maintaining the APC response at a constantly low level. On the other hand, preventing the interaction of coagulation proteins on the phospholipid surface PLa may protect them from hypercoagulation.

Antibodies, Antiphospholipid↗

PubMed1996

Arg506-Gln mutation in factor V and risk of thrombosis during pregnancy.

Seventy women with thrombosis in pregnancy were investigated for the presence of APC resistance and the associated Arg506-Gln mutation in coagulation factor V. The mutation was found in 46% of the investigated women. Carriers of the mutation were more prone to develop thrombosis in the first pregnancy (OR (odds ratio) = 3.41; P < 0.05) and had a higher probability of recurrence (OR = 3.86; P < 0.05) compared to non-carriers. The incidence of miscarriage was not related to the mutation but its probability increased in women with thrombosis in a second or subsequent pregnancy (P < 0.025). Negative dynamics of APC response during pregnancy was observed in 20/22 women; eight of them developed APC resistance de novo. The suppression of APC response was independent of the mutation.

Adolescent↗

PubMed1995

Studies on phospholipid antibodies, APC-resistance and associated mutation in the coagulation factor V gene.

The influence of antibodies against phospholipids (PLa) on APC response was investigated in 155 women with a history of thromboembolism and/or repeated foetal losses. PLa were determined as antibodies against cardiolipin (CLa) and phosphatidyl serine (PSa) and as lupus anticoagulant (LA) tested by dilute Russell's Viper Venom time and by the Textarin/Ecarin ratio. APC-response was studied by a clotting (aPTT-based) and by an amidolytic (factor IXa-X-based) assay. A reduced response to APC (APC-resistance) was found in 49% of 65 PLa-positive and in 13% of 90 PLa-negative samples (chi 2 = 23.9; p < 0.5 x 10(-4)). It was more common in the samples with LA, as compared to CLa+PSa positive (58% vs. 30%, not significant). The presence of the mutation causing Arg506-Gln substitution in coagulation factor V was investigated in 84 samples. The occurrence of the mutation in APC-resistant patients with CLa+PSa or with LA in one of the two assays was similar to those without PLa (84% and 100%, respectively). In the absence of APC resistance, the occurrence of the mutation was similar in the samples with and without PLa (14% vs. 11%). Samples with LA, determined by both tests used, comprised a special group where the frequency of the mutation in the APC resistant samples was significantly reduced (p < 0.01). In the latter samples, the pathogenic mechanism of APC resistance may be connected with the influence on phospholipid membranes.

Abortion, Habitual↗

PubMed1995

Phospholipid antibodies and resistance to activated protein C in women with thrombophilia.

Seventy-eight women with a history of thromboembolism were studied for cardiolipin antibodies (CLa), lupus anticoagulant activity (LA) and resistance to activated protein C (APC-resistance). Elevated CLa were found in 15 (19%) and LA in 15 women (19%), respectively. Twenty-six patients (33%) were APC-resistant, 17 of them had LA and/or CLa. No correlation was observed between the LA coefficient, CLa level and the extent of APC-resistance. The study shows the difference in the nature of phospholipid antibodies (PLa) and APC-resistance: cause-dependent for APC-resistance and time-dependent for the LA activity. APC-resistance was commoner in thrombosis triggered by endogenous (pregnancy, delivery) than by exogenous (oral contraceptives, surgery) factors (P < 0.05). The incidence of PLa was not connected to the cause of thrombosis. Time-dependent changes in the PLa spectrum manifested by a reduction of isolated LA frequency five years after thrombosis (P < 0.05). The response of APC seemed to show no variation with time passed after thrombosis. The co-existence of PLa and APC-resistance in 22% of thrombophilic women may stress the role of phospholipids in the blood coagulation process.

Adult↗

PubMed1995

Thrombotic risk factors and oral contraception.

Eighty-one women with a history of thrombosis were classified into three groups: group I (n = 29), women in whom thrombosis developed during oral contraception; group II (n = 33), those who used oral contraceptives (OC) without complications but experienced vascular occlusion in other risk situations; group III (n = 19), women who never used OC. The level of antibodies to anionic phospholipids (PLa), a response to activated protein C (APC), and the presence for the mutation in the coagulation factor V gene causing APC resistance were studied. In the studied groups, APC resistance was present in 14% to 42% of patients. PLa were elevated in about half of APC-resistant patients. The incidence of APC resistance correlated with the recurrency of the thrombotic events within the groups. In most cases it was tightly connected to the mutation in the factor V gene. Women in whom thrombosis developed while they were taking OC (group I) differed from the others, having a remarkable disagreement between the lowest incidence of APC resistance and a relatively increased number of the mutation (14% vs 38%, p < 0.025). This finding suggested that the APC response is flexible. An influence of OC that predisposes a reduction in APC response is discussed.

Adolescent↗

PubMed1994

A new variant of interaction between phospholipid antibodies and the protein C system.

The influence of 38 IgG fractions with either cardiolipin antibodies only (CLa) or both CLa and lupus anticoagulant activity (LA) on the response to activated protein C (APC) and on the snake venom activation of protein C were investigated. Five of eight IgG fractions with LA activity showed a tendency to reduce the effect of APC in the aPTT method and to simulate the APC-resistance phenomenon. This effect was not observed in IgG fractions without LA activity. The addition of IgG fractions did not decrease enzymatic activation of protein C in normal plasma. No correlation was found between sample protein C activity and CLa level or the extent of clotting time prolongation. These observations suggested that acquired resistance to APC in the presence of some types of phospholipid antibodies may be a cause of thrombophilia in such patients.

Adult↗