Biomedical subjects

B Bozic

Publications and source records attributed to B Bozic.

16 recordsLinked to original sources

PubMed2001

Autoantibody profiles in the sera of European patients with myositis.

OBJECTIVE: To determine the prevalence of myositis specific autoantibodies (MSAs) and several myositis associated autoantibodies (MAAs) in a large group of patients with myositis. METHODS: A total of 417 patients with myositis from 11 European countries (198 patients with polymyositis (PM), 181 with dermatomyositis (DM), and 38 with inclusion body myositis (IBM)) were serologically analysed by immunoblot, enzyme linked immunosorbent assay (ELISA) and/or immunoprecipitation. RESULTS: Autoantibodies were found in 232 sera (56%), including 157 samples (38%) which contained MSAs. The most commonly detected MSA was anti-Jo-1 (18%). Other anti-synthetase, anti-Mi-2, and anti-SRP autoantibodies were found in 3%, 14%, and 5% of the sera, respectively. A relatively high number of anti-Mi-2 positive PM sera were found (9% of PM sera). The most commonly detected MAA was anti-Ro52 (25%). Anti-PM/Scl-100, anti-PM/Scl-75, anti-Mas, anti-Ro60, anti-La, and anti-U1 snRNP autoantibodies were present in 6%, 3%, 2%, 4%, 5%, and 6% of the sera, respectively. Remarkable associations were noticed between anti-Ro52 and anti-Jo-1 autoantibodies and, in a few sera, also between anti-Jo-1 and anti-SRP or anti-Mi-2 autoantibodies. CONCLUSIONS: The incidence of most of the tested autoantibody activities in this large group of European patients is in agreement with similar studies of Japanese and American patients. The relatively high number of PM sera with anti-Mi-2 reactivity may be explained by the use of multiple recombinant fragments spanning the complete antigen. Furthermore, our data show that some sera may contain more than one type of MSA and confirm the strong association of anti-Ro52 with anti-Jo-1 reactivity.

Antibody Specificity↗

PubMed2000

Immunoserological aspects of idiopathic inflammatory muscle disease.

In the present study, the autoantibody profile of 31 Slovenian patients with idiopathic inflammatory muscle disease was estimated: 11 with polymyositis, 11 with dermatomyositis--both groups diagnosed according to the criteria of Bohan and Peter--and 9 with myositis-overlap syndromes. Autoantibodies against most relevant muscle specific (Jo-1, Mi-2) and non-specific antigens (PM-Scl, U1RNP, native Ro, Ro60, Ro52, and La) were detected with one or more detection techniques: counter-immunoelectrophoresis, enzyme-linked immunoassay, immunoblot and immunoprecipitation, each using different antigen preparations (native, recombinant). With counter-immunoelectrophoresis using a native antigen substrate (rabbit thymus extract), we were able to detect anti-PM-Scl antibodies more readily than with other techniques, probably due to conformational epitopes of native PM-Scl. Patients with this serological profile constituted a distinct group, sharing features of polymyositis and systemic sclerosis. Compared to previously reported data, the greater frequency of anti-Jo-1 found in all groups of patients (64-87% for PM, 18-20% for dermatomyositis and 33-44% for overlap syndromes) was probably due to the various methods used and the different clinical characteristics of patients. The greater prevalence of anti-Mi-2 antibodies in dermatomyositis patients (67%) and in particular in polymyositis patients (33%) and myositis-overlap syndromes (33%) seemed to be mainly due to methodological differences. A strikingly high prevalence of anti-Ro52 positive patients with polymyositis (55%), dermatomyositis (22%), and myositis-overlap syndromes (33%) was demonstrated, but was detected by only one technique. Moreover, concurrence with anti-Jo-1 antibodies was noted (69%).

Autoantibodies↗

PubMed2000

Stability analysis of micropipette aspiration of neutrophils.

During micropipette aspiration, neutrophil leukocytes exhibit a liquid-drop behavior, i.e., if a neutrophil is aspirated by a pressure larger than a certain threshold pressure, it flows continuously into the pipette. The point of the largest aspiration pressure at which the neutrophil can still be held in a stable equilibrium is called the critical point of aspiration. Here, we present a theoretical analysis of the equilibrium behavior and stability of a neutrophil during micropipette aspiration with the aim to rigorously characterize the critical point. We take the energy minimization approach, in which the critical point is well defined as the point of the stability breakdown. We use the basic liquid-drop model of neutrophil rheology extended by considering also the neutrophil elastic area expansivity. Our analysis predicts that the behavior at large pipette radii or small elastic area expansivity is close to the one predicted by the basic liquid-drop model, where the critical point is attained slightly before the projection length reaches the pipette radius. The effect of elastic area expansivity is qualitatively different at smaller pipette radii, where our analysis predicts that the critical point is attained at the projection lengths that may significantly exceed the pipette radius.

Biophysical Phenomena↗

PubMed2000

Torocyte shapes of red blood cell daughter vesicles.

The shape of the newly described torocyte red blood cell endovesicles induced by octaethyleneglycol dodecylether (C12E8) is characterized. A possible explanation for the origin and stability of the observed torocyte endovesicles is suggested. Three partly complementary mechanisms are outlined, all originating from the interaction of C12E8 molecules with the membrane. The first is a preferential intercalation of the C12E8 molecule into the inner membrane layer, resulting in a membrane invagination which may finally close, forming an inside-out endovesicle. The second is a preference of the C12E8-induced membrane inclusions (clusters) for small local curvature which would favour torocyte endovesicle shape with large regions of small or even negative membrane mean curvatures, the C12E8 membrane inclusion being defined as a complex composed of the embedded C12E8 molecule and some adjacent phospholipid molecules which are significantly distorted due to the presence of the embedded C12E8 molecule. The preference of the C12E8 inclusions for zero or negative local curvature may also lead to the nonhomogeneous lateral distribution of the C12E8 inclusions resulting in their accumulation in the membrane of torocyte endovesicles. The third possible mechanism is orientational ordering of the C12E8-induced inclusions in the regions of torocyte endovesicles with high local membrane curvature deviator.

Erythrocyte Membrane↗

PubMed2000

Pleural mesothelioma and membranous nephropathy.

Underlying malignancy has been thought to be responsible for 5-10% of the cases of membranous nephropathy in adults, with the risk being highest in patients over the age of 60 years. Solid tumors such as carcinomas of lung or colon, are most often involved. It is presumed that tumor antigens are deposited in the glomeruli; this is followed by antibody deposition and complement activation, leading to epithelial cell and basement membrane injury and proteinuria due to the associated increase in glomerular permeability. We describe a patient with a resistant nephrotic syndrome and massive proteinuria due to membranous nephropathy associated with pleural mesothelioma.

Adult↗

PubMed2000

Concomitant bihemispheric cerebral ganglioglioma and hemangioma in an 18-month-old child: case report.

This is a rare case of concomitant bihemispheric cerebral ganglioglioma and hemangioma in an 18-month-old child. There were two identical processes; a combination of ganglioglioma and hemangioma was located in the parieto-occipital region of both cerebral hemispheres. The child underwent diagnostic computed tomographic and magnetic resonance imaging examinations for seizures and right-sided facial palsy, which showed the bilateral presence of parieto-occipital, oval, well-demarcated, subcortically located processes. A biparieto-occipital craniotomy was carried out and two well-demarcated abnormalities were observed and both were removed in toto. Two years after the operation, the boy had normal psychomotor development and remained free from seizures with no therapy required. Repeat magnetic resonance imaging showed no tumor recurrence. Gangliogliomas are relatively uncommon tumors in childhood, located in the supratentorial compartment and usually associated with seizures. Histopathologic and immunohistochemical analysis of the two processes found in our patient showed them to be a ganglioglioma and a hemangioma, confirming the dysontogenetic origin of these alterations and the association between malformations and tumor growth. The combination of ganglioglioma and hemangioma, especially bilateral presentation of two such identical processes in a young child, is very rare and was not found in the recent literature.

Brain Neoplasms↗

PubMed2000

Anti-beta2-glycoprotein I ELISA: methodology, determination of cut-off values in 434 healthy Caucasians and evaluation of monoclonal antibodies as possible international standards.

Antibodies against beta2-glycoprotein I are among the most commonly detected subset of antiphospholipid antibodies. The inter-laboratory comparability of results is hardly possible due to methodological differences, lack of international standards and different cut-off values. We evaluated an ELISA for the detection of anti-beta2-glycoprotein I using the analytical goals based on biological variations for similar analytes (immunoglobulins). By our ELISA we fulfilled the optimal (IgA, IgM) or minimal (IgG) analytical goals in long-term imprecision. The determination of cut-off values was based on the frequency distribution of results obtained on 434 healthy Caucasians. To aim at a better inter-laboratory comparability we tested two monoclonal antibodies as possible calibrators: HCAL (IgG) and EY2C9 (IgM). Binding properties determined by dilutional curves showed great similarities with polyclonal sera, used as in-house standards. Cut-off values were expressed by concentrations of IgG and IgM monoclonal antibodies (4.5 and 25.3 microg/l). Our study shows the possibility for a successful application of analytical goals based on biological variation even when data for a particular analyte are not available. The expression of cut-off values, obtained on a large scale Caucasian population, by the concentration of IgG and IgM monoclonal antibodies could make possible a more reliable inter-laboratory comparison of data.

Adolescent↗

PubMed1999

Vesicle deformation by an axial load: from elongated shapes to tethered vesicles.

A sufficiently large force acting on a single point of the fluid membrane of a flaccid phospholipid vesicle is known to cause the formation of a narrow bilayer tube (tether). We analyze this phenomenon by means of general mathematical methods allowing us to determine the shapes of strongly deformed vesicles including their stability. Starting from a free vesicle with an axisymmetric, prolate equilibrium shape, we consider an axial load that pulls (or pushes) the poles of the vesicle apart. Arranging the resulting shapes of strained vesicles in dependence of the axial deformation and of the area difference of monolayers, phase diagrams of stable shapes are presented comprising prolate shapes with or without equatorial mirror symmetry. For realistic values of membrane parameters, we study the force-extension relation of strained vesicles, and we demonstrate in detail how the initially elongated shape of an axially stretched vesicle transforms into a shape involving a membrane tether. This tethering transition may be continuous or discontinuous. If the free vesicle is mirror symmetric, the mirror symmetry is broken as the tether forms. The stability analysis of tethered shapes reveals that, for the considered vesicles, the stable shape is always asymmetric (polar), i.e., it involves only a single tether on one side of the main vesicle body. Although a bilayer tube formed from a closed vesicle is not an ideal cylinder, we show that, for most practical purposes, it is safe to assume a cylindrical geometry of tethers. This analysis is supplemented by the documentation of a prototype experiment supporting our theoretical predictions. It shows that the currently accepted model for the description of lipid-bilayer elasticity (generalized bilayer couple model) properly accounts for the tethering phenomenon.

Biophysical Phenomena↗

PubMed1997

Influence of degraded phosphatidylserine on binding of antiphospholipid antibodies.

BACKGROUND: Antiphospholipid antibodies (aPL) show great heterogeneity. Different phospholipids, with or without protein cofactor(s), and phospholipid binding proteins alone have been proposed as the target molecules for aPL. In order to determine the influence of phospholipid degradation products on the binding of aPL, sera from 6 patients with the antiphospholipid syndrome were studied. METHODS: Fresh and aged phosphatidylserine and cardiolipin were used as coating reagents in solid-phase immunoassay procedures. Antibody reactivity was tested by enzyme-linked immunosorbent assay in the sera and in eluates from columns packed with polystyrene scrapings coated with either cardiolipin or phoshatidylserine. RESULTS: Three reaction patterns of affinity-purified antibodies were seen: (1) reactivity with phosphatidylserine but not with cardiolipin or degraded phosphatidylserine, (2) reactivity with cardiolipin and degraded phosphatidlyserine, and (3) reactivity with all three phospholipid antigens. CONCLUSIONS: Striking differences in the antiphospholipid antibody reactivity with cardiolipin, phosphatidylserine and degraded phosphatidylserine in the presence of serum proteins were observed among patients with venous thromboembolism. The analyses showed that the degradation of phosphatidylserine influences the binding of aPL in in vitro assays.

Adolescent↗

PubMed1996

A decrease in antiphospholipid antibodies before a thrombotic event.

We are reporting a systemic lupus erythematosus patient with antiphospholipid syndrome who developed iliofemoral thrombosis. Before the occurrence of iliofemoral venous thrombosis, antiphospholipid antibodies (aPL) gradually decreased over a period of 18 weeks but were within normal range during its acute phase. In the course of two years following this case of thrombosis, aPL have never returned to the high prethrombotic values. It is therefore most likely that aPL were involved in the process of provoking thrombosis rather than being consumed during its acute phase.

Antibodies, Antiphospholipid↗

PubMed1993

Sera from patients with rheumatic diseases recognize different epitope regions on the 52-kD Ro/SS-A protein.

Patients suffering from systemic lupus erythematosus (SLE) or Sjögren's syndrome (SS) often contain autoantibodies directed to the Ro(SS-A) complex. In this study the antigenic determinants on two of the components of the Ro complex, i.e. the Ro60 and the Ro52 polypeptides, were investigated. Anti-Ro+ sera were selected by counter-immunoelectrophoresis. Depending on the detection method, 59-68% of the SLE patients produced anti-Ro but not anti-La antibody, while 72-81% of the SS patients produced both anti-Ro and anti-La antibody. Immunoprecipitation of recombinant Ro-proteins showed that 61 sera (87%) were reactive with both Ro proteins, seven sera with Ro60 only, one serum with Ro52 only, and one serum did not precipitate the proteins at all. The anti-Ro60 reactivity of human sera is strongly associated with the native form of Ro60, suggesting that conformational autoepitopes are an important feature of Ro60. In the case of Ro52, frequently the residues located between amino acids 216 and 292 were essential for reactivity with the antibodies. With 70% of the lupus sera tested this appeared to be the only region important for reactivity. The antibodies of SS patients generally recognized multiple B cell epitopes located between amino acids 55 and 292. The results of this study indicate that the antigenic determinants on Ro52 are different for autoantibodies produced by lupus patients compared with those of SS patients.

Adolescent↗

PubMed1993

The dissociation of arterial hypertension and lupus glomerulonephritis in systemic lupus erythematosus.

In spite of several articles questioning the general opinion that arterial hypertension in patients with systemic lupus erythematosus (SLE) is only the consequence of lupus glomerulonephritis (LGN), this still remains the usual pathophysiologic explanation. The purpose of this study was to explore the correlations between hypertension and LGN and to assess the importance of hypertension control for the prognosis of patients. A retrospective analysis of 173 patients with SLE over a period of 14 years was performed. For most of the patients, data were available from regular follow-up visits over an average of 6 years. Our results show a dissociation of hypertension and LGN and an association of hypertension and renal dysfunction. Severe hypertensive renal vascular lesions correlated well with a decrease of renal function. Successful treatment of hypertension is therefore essential in order to prevent deterioration of renal function in patients with LGN.

Adolescent↗

PubMed1992

Refined definition of the 56K and other autoantigens in the 50-60 kDa region.

Alteration of the acrylamide:bisacrylamide ratio in the SDS-polyacrylamide gel used for Western blotting strongly improved the unambiguous detection of antibodies against 50-60 kDa autoantigens present in autoimmune patient sera. The relative migration of Ro52, the 56K autoantigen and calreticulin increased with reduced acrylamide:bisacrylamide ratios in contrast to that of Ro60, La and Jo-1. These analyses indicated that these six autoantigens correspond to six distinct polypeptides. Further analyses using recombinant calreticulin showed that (i) the 56K autoantigen is neither identical nor related to calreticulin and (ii) calreticulin is not a Ro autoantigen. A series of experiments designed to better characterize the 56K autoantigen showed that (i) the antigen is not detectable in fixed cells, presumably due to masking of the epitopes; (ii) about equal amounts of the antigen were recovered in nuclear and cytoplasmic cell fractions after enucleation of the cells; (iii) the 56K autoantigen is not stably associated with either RNA or other proteins.

Animals↗

PubMed1992

Role of lamellar membrane structure in tether formation from bilayer vesicles.

A theoretical analysis is presented of the formation of membrane tethers from micropipette-aspirated phospholipid vesicles. In particular, it is taken into account that the phospholipid membrane is composed of two layers which are in contact but unconnected. The elastic energy of the bilayer is taken to be the sum of contributions from area expansivity, relative expansivity of the two monolayers, and bending. The vesicle is aspirated into a pipette and a constant point force is applied at the opposite side in the direction away from the pipette. The shape of the vesicle in approximated as a cylindrical projection into the pipette with a hemispherical cap, a spherical section, and a cylindrical tether with a hemispherical cap. The dimensions of the different regions of the vesicle are obtained by minimizing its elastic energy subject to the condition that the volume of the vesicle is fixed. The range of values for the parameters of the system is determined at which the existence of a tether is possible. Stability analysis is performed showing which of these configurations are stable. The importance of the relative expansion and compression of the constituent monolayers is established by recognizing that local bending energy by itself does not stabilize the vesicle geometry, and that in the limit as the relative expansivity modulus becomes infinitely large, a tether cannot be formed. Predictions are made for the functional relationships among experimentally observable quantities. In a companion report, the results of this analysis are applied to experimental measurements of tether formation, and used to calculate values for the membrane material coefficients.

Biophysical Phenomena↗

PubMed1991

Prevalence of antiphospholipid antibodies in deep vein thrombosis and their relationship to blood coagulation and fibrinolysis.

Elevated levels of antiphospholipid antibodies are associated with an increased risk of thrombosis. To establish the prevalence of these antibodies in deep vein thrombosis (DVT), IgG and IgM antibodies to cardiolipin (aCL) and phosphatidylserine (aPS) were determined by enzyme-linked immunosorbent assay in 118 patients with DVT either during an acute episode (N = 53) or at least 2 months after acute DVT (N = 65). Most patients (76%) had proximal leg DVT and no one had evident autoimmune disorder. aCL and aPS values higher than 4 standard deviations above the mean value of the control group (147 blood donors) were considered increased. Increased IgG aCL were observed in 10% of DVT patients (controls: 5%, not significant), increased IgG aPS in 16% of DVT patients (controls: 5%, p less than 0.005) and both types in 4% of DVT patients (controls: 3%, not significant). In the subgroup of 41 patients with previous idiopathic DVT, prevalence of increased IgG aPS was the highest: 27% (p less than 0.001). Increased antibodies of IgM isotype were observed in 3% (aCL) and 2% (aPS) of all DVT patients (controls: 8% and 4%, respectively, not significant). Elevated IgG aCL or aPS were not associated with significant changes in platelet count, antithrombin III and protein C. However, in patients with increased IgG aPS deficient fibrinolysis due to high plasminogen activator inhibitor activity was observed before and after 20 min upper arm venous occlusion. DVT patients with increased IgG aPS might be exposed to a greater risk of rethrombosis due to deficient fibrinolysis than DVT patients without these antibodies.

Adolescent↗

PubMedDate not supplied

Fluctuation of anti-Ro/SS-A antibody levels in patients with systemic lupus erythematosus and Sjögren's syndrome: a prospective study.

OBJECTIVE: To determine whether the titers of anti-Ro/SS-A (Ro) antibodies fluctuate during the course of SLE and Sjögren's syndrome (SS) in parallel with disease activity, and if such fluctuations could be used to predict disease flares. We also evaluated whether the anti-Ro profile (anti-Ro 52, anti-Ro 60) changes over time, since such information could provide new insights into the induction and regulation of anti-Ro autoimmunity. METHODS: Sixteen patients with SLE and 15 patients with SS, all anti-Ro/SS-A antibody positive, were followed up for two years at three-month intervals. Clinical and laboratory parameters of disease activity were examined. Determination of the anti-Ro/SS-A titer was performed by counterimmunoelectrophoresis and the fine anti-Ro antibody specificity was determined by immunoblotting. RESULTS: The titers of anti-Ro antibodies fluctuated during the course of the illness in both SLE and SS patients. In SLE patients these changes were not (except in one case) associated with disease activity nor were they predictive of disease flares. The same was true for the SS patients, with the exception of two patients with skin vasculitis in whom anti-Ro antibody titers fluctuated in parallel with the disease activity. The anti-Ro antibody (anti-Ro 60 kD, anti-Ro 52 kD) specificity did not change in any of the patients during the follow-up period. CONCLUSION: Anti-Ro antibodies could represent a valuable indicator of disease activity in SS patients with cutaneous disorders. They do not, on the other hand, reflect disease activity in patients with SLE. The stable antibody profile in both SLE and SS patients supports the hypothesis that autoantibody production is predominantly genetically regulated.

Adolescent↗