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Biomedical subjects

C A Laskin

Publications and source records attributed to C A Laskin.

At least 19 recordsLinked to original sources
PubMed2000

Prevalence of antibodies to beta2-glycoprotein I in systemic lupus erythematosus and their association with antiphospholipid antibody syndrome criteria: a single center study and literature review.

OBJECTIVE: To determine the prevalence of anti-beta2-glycoprotein I antibodies (anti-beta2-GPI) in patients with systemic lupus erythematosus (SLE), and to assess their association with and predictive value for the clinical classification criteria of the antiphospholipid antibody syndrome (APS). METHODS: One hundred thirty-three consecutive patients with SLE were recruited from 2 lupus clinics in the University of Toronto. Serum and plasma samples were tested for IgG anticardiolipin antibodies (aCL), prolonged partial thromboplastin time (PTT), a panel of lupus anticoagulant (LAC) assays, and anti-beta2-GPI (IgG, IgM, IgA). Normal ranges for the assays were established using 129 healthy controls. A literature review from 1992 to 2000 was performed using beta2-GPI, SLE, APS, thrombosis, and recurrent pregnancy loss as key search words. RESULTS: The distribution of anti-beta2-GPI antibodies (of any isotype) in each group were as follows: all patients with SLE, 36.8%; SLE with clinical features of APS, 40.4%; SLE without clinical features of APS, 34.9%; and healthy controls, 3%. The positive predictive values of prolonged PTT, IgG aCL, and anti-beta2-GPI for at least one clinical feature of APS in SLE were 59.3, 50.0, and 38.8%, respectively. There were 27 patients with SLE who had antibodies to beta2-GPI but a normal PTT and negative aCL and LAC. Six (20.7%) of these had a history of thrombosis and/or recurrent pregnancy loss. Twelve studies (including ours) were identified in which patient groups were similar and the same antibody isotype was measured. No agreement was apparent after reviewing the literature regarding an association of anti-beta2-GPI IgG and clinical features of APS in patients with SLE. CONCLUSION: Antibodies to beta2-GPI were frequently seen (35%) in our SLE population. The prevalence of anti-beta2-GPI was similar in those with (19/47) and without (39/86) APS. Anti-beta2-GPI did, however, identify 6 patients with clinical features of APS who were negative for aCL and prolonged PTT. Our results indicate that anti-beta2-GPI may provide additional information for the diagnosis of APS in SLE, but do not supercede other established assays. However, when we attempted to place our results in the context of other reports, the literature review revealed that secondary diagnoses of patient groups and assay techniques are too variable among different investigators to allow useful comparison. Thus, no conclusions could be drawn regarding anti-beta3-GPI and clinical features of secondary APS in SLE.

Adolescent↗
PubMed1999

Folic acid and homocyst(e)ine metabolic defects and the risk of placental abruption, pre-eclampsia and spontaneous pregnancy loss: A systematic review.

Placental infarction or abruption, recurrent pregnancy loss and pre-eclampsia are thought to arise due to defects within the placental vascular bed. Deficiencies of vitamin B12 and folate, or other abnormalities within the methionine-homocyst(e)ine pathway have been implicated in the development of such placental diseases. We conducted a systematic literature review to quantify the risk of placental disease in the presence of these metabolic defects. Studies were identified through OVID Medline between 1966 and February 1999. Terms relating to the measurement of vitamin B12, folic acid, methylenetetrahydrofolate reductase or homocyst(e)ine were combined with those of pre-eclampsia, placental abruption/infarction or spontaneous and habitual abortion. Human studies comprising both cases and controls and published in the English language were accepted. Their references were explored for other publications. Data were abstracted on the matching of cases with controls, the mean levels of folate, B12 or homocyst(e)ine in each group or the frequency of the homozygous state for the thermolabile variant of methylenetetrahydrofolate reductase. The definition of 'abnormal' for each exposure was noted and the presence or absence of the exposure of interest for each outcome was calculated as an absolute rate with a 95 per cent confidence interval. The crude odds ratios were calculated for each study and then pooled using a random effects model. Eighteen studies were finally included. Eight studies examined the risk of placental abruption/infarction in the presence of vitamin B12 or folate deficiency, or hyperhomocyst(e)inaemia. Folate deficiency was a prominent risk factor for placental abruption/infarction among four studies, though not statistically significant (pooled odds ratio 25.9, 95 per cent CI 0.9-736.3). Hyperhomocyst(e)inaemia was also associated with placental abruption/infarction both without (pooled odds ratio 5.3, 95 per cent CI 1.8-15.9) and with methionine loading (pooled odds ratio 4.2, 95 per cent CI 1.2-15.0), as was the homozygous state for methylenetetrahydrofolate reductase (pooled odds ratio 2.3, 95 per cent CI 1.1-4.9). Vitamin B12 deficiency was not a demonstrable risk factor. Eight studies examined blood levels among women with spontaneous abortion or recurrent pregnancy loss. The pooled odds ratios were 3.4 (95 per cent CI 1.2-9.9) for folate deficiency, 3.7 (95 per cent CI 0.96-16.5) for hyperhomocyst(e)inaemia following methionine challenge, and 3.3 (95 per cent CI 1.2-9.2) for the methylenetetrahydrofolate reductase mutation. Five case-control studies examined the relationship between pre-eclampsia and abnormal levels of vitamin B12, folate, homocyst(e)ine or methylenetetrahydrofolate reductase. Folate deficiency was not an associated risk factor (odds ratio 1.2, 95 per cent CI 0.5-2.7), but hyper-homocyst(e)inaemia was (pooled odds ratio 20.9, 95 per cent CI 3.6-121.6). Similarly, homozygosity for the methylenetetrahydrofolate reductase thermolabile variant was associated with a moderate risk of preeclampsia (odds ratio 2.6, 95 per cent CI 1.4-5.1). Some pooled data were associated with significant statistical heterogeneity, however. There is a general agreement among several observational studies that folate deficiency, hyperhomocyst(e)inaemia and homozygosity for the methylenetetrahydrofolate reductase thermolabile variant are probable risk factors for placenta-mediated diseases, such as pre-eclampsia, spontaneous abortion and placental abruption. Vitamin B12 deficiency is less well defined as an important risk factor. Due to the limited quality of these data, including insufficient matching of cases with controls, and possible laboratory measurement bias relating to pregnancy, prospective studies are needed to confirm these findings and guide future preventative and therapeutic research.

Female↗
PubMed1999

The effects of low-intensity warfarin on coagulation activation in patients with antiphospholipid antibodies and systemic lupus erythematosus.

The optimal intensity of oral anticoagulant therapy for the prevention of thromboembolism in patients with antiphospholipid antibodies (APLA) and systemic lupus erythematosus is controversial. Retrospective studies have suggested that patients with APLA are resistant to oral anticoagulant therapy, with a targeted International Normalization Ratio (INR) of 2.0 to 3.0, and that a higher intensity of anticoagulation (INR: 2.6 to 4.5) is required to prevent recurrent thromboembolism. To investigate if patients with APLA are resistant to the anticoagulant effect of low intensities of warfarin therapy, we performed a randomized trial in which 21 patients with APLA and systemic lupus erythematosus were allocated to receive one of three intensities of warfarin (INR: 1.1 to 1.4, 1.5 to 1.9 or 2.0 to 2.5) or placebo for four months. The main outcome was the effect of each intensity of warfarin therapy on prothrombin fragment 1+2 level (F1+2), that was used as a marker of coagulation activation. When F1+2 levels in patients allocated to the three warfarin intensities were compared to F1+2 levels in the placebo group, there was a statistically significant decrease (p<0.05) in the patient group receiving warfarin with a targeted INR of 2.0 to 2.5 at two, three and four months, and in the patient group with a targeted of INR 1.5 to 1.9 at three months. We conclude that in patients with APLA and systemic lupus erythematosus, warfarin therapy, with a targeted INR of 2.0 to 2.5, is effective in suppressing coagulation activation, and therefore, might be effective in preventing thromboembolism.

Adolescent↗
PubMed1997

Prednisone and aspirin in women with autoantibodies and unexplained recurrent fetal loss.

BACKGROUND: Recurrent fetal loss has been well described in women with antiphospholipid antibodies. Such women also often have other autoantibodies commonly found in patients with systemic lupus erythematosus. Treating them with prednisone and aspirin may reduce the risk of fetal loss. METHODS: We screened 773 nonpregnant women who had the unexplained loss of at least two fetuses for antinuclear, anti-DNA, antilymphocyte, and anticardiolipin antibodies and for the lupus anticoagulant. Of 385 women with at least one autoantibody, 202 who later became pregnant were randomly assigned in equal numbers to receive either prednisone (0.5 to 0.8 mg per kilogram of body weight per day) and aspirin (100 mg per day) or placebo for the duration of the pregnancy. The women were stratified according to age (18 to 34 years or 35 to 39 years) and the week of gestation at which the previous fetal losses had occurred (< or = 12 or > 12 weeks). The primary outcome measure was a successful pregnancy. RESULTS: Live infants were born to 66 women in the treatment group (65 percent) and 57 women in the placebo group (56 percent, P=0.19). More infants were born prematurely in the treatment group than in the placebo group (62 percent vs. 12 percent, P<0.001). The major side effects of therapy in the mothers were hypertension (treatment group, 13 percent; placebo group, 5 percent; P=0.05) and diabetes mellitus (15 percent and 5 percent, P=0.02). CONCLUSIONS: Treating women who have autoantibodies and recurrent fetal loss with prednisone and aspirin is not effective in promoting live birth, and it increases the risk of prematurity.

Abortion, Habitual↗
PubMed1994

Sera from habitual aborters induce monocyte procoagulant activity: a lymphocyte-dependent event.

Placental thrombosis is a prominent feature in patients with unexplained recurrent fetal loss. To determine whether induction of monocyte procoagulant activity might be a relevant mechanism for unexplained recurrent fetal loss, peripheral blood mononuclear cells isolated from normal healthy controls were cocultured with (a) sera from normal healthy controls (n = 16), (b) sera from habitual aborters (n = 41), and (c) lipopolysaccharide as a positive control. Sera from three patients were fractionated on Sephracryl S-300 and the inducing molecule(s) characterized. Sera from normal healthy controls failed to induce procoagulant activity above basal levels of 21 +/- 4.6 mU/10(5) peripheral blood mononuclear cells. Of the sera from 41 habitual aborters examined 26 (63%) induced procoagulant to a mean value of 410 +/- 48 mU/10(5) peripheral blood mononuclear cells (P < 0.01). Sera from 15 patients failed to augment procoagulant activity. The induction of procoagulant activity was maximal after 6 hr of incubation and was lymphocyte dependent. Fractionation of serum from the three patients on Sepharcryl S300 revealed the procoagulant activity (PCA)-inducing factor(s) to have a molecular weight of between 300,000 and 800,000 Da. The serum factor was found to be heat, alkaline, and acid sensitive. Both anti-IgM and anti-IgA immunoabsorbents reduced the PCA-inducing factor. We conclude that IgM and IgA from some patients with unexplained recurrent fetal loss are capable of inducing procoagulant activity and could contribute to the development of placental microthrombi and infarction, prominent features of this syndrome.

Abortion, Habitual↗
PubMed1991

Clinical utility and specificity of anticardiolipin antibodies.

Established solid phase assays for anticardiolipin antibodies (aCL) are often characterized by high levels of nonspecific binding. As a result, only very high levels of aCL have been reported to be associated with a variety of clinical conditions including systemic lupus erythematosus (SLE), recurrent intravascular thrombosis and unexplained recurrent fetal loss. We have developed an ELISA replacing direct evaporation of soluble cardiolipin with cardiolipin micelles in physiological saline as the antigen binding step in the assay. Levels of IgG aCL were detected in various sera at dilutions of 1/100 to 1/3200, showing improved assay sensitivity. Assay specificity was determined using double stranded DNA and ovalbumin as irrelevant binding antigens and no crossreactivity was found. The controversial use of Tween 20 in the assay was investigated and results showed it decreases nonspecific binding without interfering in antibody detection. This assay has enabled us to identify differences in the prevalence and level of aCL antibodies in sera from healthy nonpregnant controls (0/25 positive), healthy pregnant controls (5/47 positive for IgG and 8/47 positive for IgM) and from women with unexplained recurrent fetal loss (16/62 and 14/62 positive, respectively). We support the observation that aCL are not normally distributed, and therefore nonparametric methods of statistical analysis are necessary to determine population prevalence. We confirm that aCL IgM are a relatively nonspecific finding, and extreme caution must be used in basing any clinical decisions on the presence of this antibody alone.

Adolescent↗
PubMed1990

Autoantibodies in alcoholic liver disease.

PURPOSE: To test the hypothesis that since only a proportion of heavy drinkers develop significant alcoholic liver disease (ALD), an autoimmune pathogenesis is likely. PATIENTS AND METHODS: Autoimmune markers were measured in 47 patients with biopsy-proven ALD and compared to measurements in 20 alcoholics without clinical and hematologic evidence of ALD and 28 patients with autoimmune chronic active hepatitis (CAH). RESULTS: Twenty-two percent of patients with ALD were antinuclear antibody-positive, compared to 71% of patients with CAH. Approximately 60% of patients with ALD had either anti-single-stranded or anti-double-stranded DNA antibodies, slightly more than the patients with CAH. Another marker of autoimmunity, as in systemic lupus erythematosus, is the presence of IgM antibodies to autologous and heterologous lymphocytes, which are cytotoxic at 4 degrees C. Seventy-two percent of patients with CAH had positive antilymphocyte antibodies, compared to 59.6% of patients with ALD. Furthermore, more than 90% of the sera from ALD and CAH patients displayed lymphocytotoxicity. Thirty-two percent and 25.5% of CAH and ALD patients, respectively, had all three autoantibodies present. CONCLUSION: These results suggest that autoimmune mechanisms may indeed play a role in the pathogenesis of ALD in at least some patients.

Adult↗
PubMed1990

Ancrod improves survival in murine systemic lupus erythematosus.

The effect of ancrod, a defibrinating agent, on murine lupus glomerulonephritis in the male BXSB mouse was studied to determine the relationship between macrophage procoagulant activity (PCA), fibrin deposition and glomerulonephritis. Marked renal disease and fibrin deposition were noted by three months of age in control mice, whereas little or no disease was seen in ancrod treated mice until five months of age. Similar high titers of anti-DNA antibodies and renal deposition of IgG were seen in both groups of mice. PCA rose with age in both ancrod treated and untreated mice, although it was significantly higher in control animals than in the ancrod treated group. Furthermore, ancrod therapy resulted in a decrease in plasma PCA inducing activity (PIF) and a decrease in the effectiveness of PIF to induce PCA in peritoneal macrophages in vitro. No mortality was observed in the 20 ancrod treated mice, whereas 10 of 20 control animals died. We conclude that defibrination with ancrod delays the development of renal fibrin deposition and glomerulonephritis and improves survival in BXSB mice. This was associated with a decrease in plasma PCA inducing activity and with an inhibitory effect on PCA induction. These results suggest that PCA contributes to injury in murine lupus glomerulonephritis by promoting fibrin deposition.

Ancrod↗
PubMed1990

A human anti-cardiolipin autoantibody is encoded by developementally restricted heavy and light chain variable region genes.

Based on recent structural analyses of monoclonal autoantibodies, it appears that a number of these antibodies express germ-line immunoglobulin variable region (V) genes with little or no somatic mutation. In addition, our group and others have noted the identity or near identity of some autoantibody-associated V genes to V genes apparently expressed preferentially in the fetal pre-B cell repertoire. To extend these data, we now report that the heavy and light chain V genes of an anti-cardiolipin antibody derived from a healthy individual display 99% nucleotide sequence homology with V genes expressed in early B cell ontogeny. Sequence comparisons indicate the likely use of fetal-restricted V genes by this autoantibody. Taken together with other data on autoantibody V gene usage, these findings provide further evidence for overlap between the autoantibody-associated and early ontogeny expressed V gene repertoires and suggest that natural autoreactivity may be instrumental in the development and maintenance of the normal immune repertoire.

Amino Acid Sequence↗
PubMed1989

Anti-DNA and antilymphocyte antibodies during acute infection with human parvovirus B19.

Sera from patients in the acute and recovery stages of parvovirus B19 infection, and from individuals with no detectable antiparvovirus antibody were examined for the presence of anti-DNA and antilymphocyte antibodies. Sixty-eight percent of individuals recently recovered from parvovirus infection had elevated levels of antidouble stranded (ds) and antisingle stranded (ss) DNA antibodies. In addition, a cytotoxic IgM antilymphocyte antibody was detected in more than 88% of these same sera. Serial specimens from volunteers experimentally infected with parvovirus B19 were also tested for these autoantibodies and it was determined that the presence of antilymphocyte IgM was dependent on the stage of infection. The antilymphocyte IgM was occasionally detectable in sera containing rubella specific IgM (11%) or varicella zoster specific IgM (25%). However, in contrast to B19 infection, these antibodies were not cytotoxic. From the results of our study, we propose that parvovirus infection of hematologically normal individuals may be accompanied by a transient, subclinical autoimmune state.

Antilymphocyte Serum↗
PubMed1988

Lupus pregnancy. A prospective study of placental changes.

Eleven patients with systemic lupus erythematosus (SLE) were monitored prospectively during pregnancy. Clinical and serologic features of disease activity were recorded, and after delivery, a careful search for pathologic changes in the placenta was carried out. Seven patients delivered live infants, and 4 patients had unsuccessful pregnancies, with fetal loss occurring between 12 and 27 weeks of gestation. One of these 4 patients had active SLE at delivery, and all had circulating lupus anticoagulant and thrombocytopenia. Other serologic abnormalities, including anticardiolipin and anti-Ro antibodies, were not associated with fetal loss. The overall placental size was reduced in SLE patients compared with that in healthy controls and in diabetic controls. A variety of pathologic changes were noted, including placental infarction, intraplacental hematoma, deposition of immunoglobulin and complement, and thickening of the trophoblast basement membrane. The reduction in placental size appeared to enhance the clinical significance of these pathologic changes.

Antibodies↗
PubMed1986

The regulatory role of NZB T lymphocytes in the production of anti-DNA antibodies in vitro.

Murine lupus is characterized by the production of numerous autoantibodies and immune complex glomerulonephritis. Anti-DNA antibodies are the hallmark of this disorder and may be associated pathogenetically with the glomerulonephritis. The cellular mechanisms underlying the regulation of the production of anti-DNA antibodies may prove to be the fundamental abnormalities responsible for the lupus syndrome seen in these mice. By using a system of spontaneous anti-DNA antibody production in vitro, we have determined that such production is characteristic of autoimmune NZB and MRL-lpr/lpr mice but not of the nonautoimmune control strains. Additional examination of the cellular mechanisms involved in the regulation of this response in NZB mice revealed: 1) this response is markedly T cell dependent, 2) NZB T cells are essential for maximal production of this autoantibody, and 3) NZB T cells actively interfere with normal immune regulatory mechanisms that lead to the production of anti-DNA antibodies spontaneously in vitro by nonautoimmune syngeneic B lymphocytes. Although these studies of anti-DNA antibody production in vitro disagree with previous work by others they successfully reproduce the results obtained earlier in experiments performed in vivo.

Animals↗