PubMed Health⌕ Search

Biomedical subjects

Marcin Czerwinski

Publications and source records attributed to Marcin Czerwinski.

11 recordsLinked to original sources
PubMed2007

Mouse models of IgG- and IgM-mediated hemolysis.

Well-characterized mouse models of allo-immune antibody-mediated hemolysis would provide a valuable approach for gaining greater insight into the pathophysiology of hemolytic transfusion reactions. To this end, mouse red blood cells (mRBCs) from human glycophorin A transgenic (hGPA-Tg) donor mice were transfused into non-Tg recipients that had been passively immunized with IgG or IgM hGPA-specific monoclonal antibodies (mAbs). In this novel murine "blood group system," mRBCs from hGPA-Tg mice are "antigen positive" and mRBCs from non-Tg mice are "antigen negative." Passive immunization of non-Tg mice with the IgG1 10F7 and IgG3 NaM10-2H12 anti-hGPA mAbs each induced rapid clearance of incompatible transfused hGPA-Tg-mRBCs in a dose-response manner. Using various knockout mice as transfusion recipients, both the complement system and activating Fcgamma receptors were found to be important in the clearance of incompatible mRBCs by each of these IgG mAbs. In addition, the IgM E4 anti-hGPA mAb induced complement-dependent intravascular hemolysis of transfused incompatible hGPA-Tg-mRBCs accompanied by gross hemoglobinuria. These initial studies validate the relevance of these new mouse models for addressing important questions in the field of transfusion medicine.

Animals↗
PubMed2006

Condylar fracture repair: use of the endoscope to advance traditional treatment philosophy.

Traditional treatment of subcondylar fractures with maxillomandibular fixation often results in a malreduction and significant functional and aesthetic sequelae, including facial asymmetry, decreased jaw opening, and potential for late derangements of the temporomandibular joint. When used selectively, based on preoperative CT scans, the endoscopic technique will reliably restore condylar anatomy in nearly 95% of patients, thus obviating the consequences of malunion. Furthermore, unlike traditional open techniques no significant facial scarring or permanent facial nerve palsies have resulted. Thus, the authors strongly advocate endoscopic repair of adult condylar neck and subcondylar fractures that demonstrate displacement or dislocation and have adequate proximal bone stock to accept miniplate fixation.

Endoscopy↗
PubMed2006

The rationale and technique of endoscopic approach to the zygomatic arch in facial trauma.

The reliable form and strategic position of the zygomatic arch make it a valuable landmark in midfacial trauma management. The benefits of arch repair have been used infrequently, mainly because traditional coronal access to this structure is fraught with undesirable sequelae. Endoscope-assisted zygomatic arch realignment and fixation allow anatomic repair without sustaining the drawbacks of extensive access incisions. The relative importance of this approach increases with trauma complexity, being most useful in Le Fort III and complex zygoma injuries.

Endoscopy↗
PubMed2005

Quantitative topographical evaluation of the orbitozygomatic complex.

BACKGROUND: The orbitozygomatic complex is a tetrapod-shaped bone of the upper midfacial skeleton of particular clinical significance. By defining the malar prominence, it provides a significant contribution to the overall facial form. Moreover, it is the second most frequently fractured bone on the craniofacial skeleton. A method for quantitative determination of the position of the orbitozygomatic complex has important applications in the fields of reconstructive and aesthetic plastic surgery. METHODS: Ten individuals were evaluated using craniofacial anthropometry techniques. The position of the orbitozygomatic complex in three planes, x, y, and z, was determined by measuring linear projective distances between complex landmarks: the maxillozygion (the most prominent landmark on the malar prominence), the orbitale (the lowest point on the inferior orbital rim), the zygion (the most lateral point on the zygomatic arch), and the cranial reference landmarks (the vertex, opisthocranion, and nasion). RESULTS AND CONCLUSIONS: Low variability between measurements within the same individual (<1.5 mm) underscores the reliability of the chosen landmarks and techniques in the determination of orbitozygomatic complex position. Second, the complex occupies a consistent position among individuals, as shown by the low intersubject variability. Third, there is no statistically significant difference in the position of the complex, in any plane of space, between the left and right sides of the face. Thus, the authors' method may be used to determine the degree of complex displacement in individuals with unilateral facial trauma or with unilateral residual postsurgical deformity, and to calculate the amount of realignment needed to produce a symmetrical facial appearance.

Adult↗
PubMed2005

Quantitative comparison of open reduction and internal fixation versus the Gillies method in the treatment of orbitozygomatic complex fractures.

BACKGROUND: Precise repair of orbitozygomatic complex fractures is essential for proper re-establishment of facial symmetry, ocular globe position, and infraorbital nerve function. Controversy regarding the optimal treatment method remains. METHODS: To compare uniform study groups, only patients without previous craniofacial injuries or operations who had sustained moderate-energy orbitozygomatic complex fractures, based on preoperative computed tomography scans, and who were treated using the Gillies repair or open reduction and internal fixation were selected. Quantifiable end-points, including orbitozygomatic complex position, ocular globe projection, and infraorbital nerve function, were measured to objectively compare the accuracy of repair produced by the Gillies procedure and open reduction and internal fixation. Negative sequelae resulting from cutaneous access were tabulated. RESULTS: Overall, 12 patients treated using the Gillies repair and 12 treated with open reduction and internal fixation were examined. The results demonstrated that the open reduction and internal fixation technique produces superior realignment of the orbitozygomatic complex, that is, a smaller difference in the position of the orbitozygomatic complex between the injured and noninjured sides of the face. The differences in orbitozygomatic complex projection, height, and lateral position were 1.4 mm, 1.4 mm, and 1.6 mm, respectively, in the open reduction and internal fixation group and 7.5 mm, 5.6 mm, and 4.1 mm in the Gillies group. The p values were 0.0003, 0.01, and 0.06, respectively. Visible cutaneous scarring was present in four patients and lower lid shortening was seen in three patients treated using open reduction and internal fixation. CONCLUSIONS: To the authors' knowledge, this is the first study to objectively show that the open reduction and internal fixation technique results in superior positioning of the orbitozygomatic complex in moderate-energy orbitozygomatic complex fractures compared with the Gillies repair. Although negative sequelae from surgical access were substantial, recently introduced transconjunctival and upper lid blepharoplasty incisions will minimize these drawbacks.

Adult↗
PubMed2004

Purification, crystallization and X-ray diffraction analysis of a recombinant Fab that recognizes a human blood-group antigen.

The NNA7 Fab fragment recognizes the human glycopeptide N blood-group antigen and has a high affinity for N-type glycophorin A (GPA). To provide insight into how antibodies recognize glycopeptide antigens, soluble Fab fragments were expressed in Escherichia coli, purified and crystallized using the hanging-drop vapor-diffusion method at 293 K. The best crystals were obtained from solutions of PEG monomethyl ether 5000 containing 4-8 mM yttrium chloride (YCl3). This rare-earth ion, which could be substituted with various lanthanides, changed the habit of crystals from multinucleated rods with a diffraction limit of 4.25 A resolution to a diamond-shaped morphology that grew as single crystals and diffracted X-rays to 1.75 A resolution. Data were collected that indicated that the crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 57.9, b = 77.1, c = 118.1 A and one Fab fragment per asymmetric unit. A molecular-replacement solution has been obtained and 86% of the molecule was fitted by use of an automated refinement procedure (ARP).

Antigen-Antibody Complex↗
PubMed2004

Traumatic arch injury: indications and an endoscopic method of repair.

The unique strategic position of the zygomatic arch makes it an important surgical landmark in facial fracture repair. Because of the numerous negative sequelae associated with the traditional coronal approach to the arch, it has frequently been omitted as a point of reduction and fixation. Endoscope-assisted repair allows accurate zygomatic arch restoration without the setbacks of coronal access. The indications for arch repair include markedly displaced isolated arch fractures, complex zygoma fractures with arch comminution, and Le Fort III level fractures. In complex zygoma fractures, the arch helps accurately restore midface projection and width and serves as an additional stable anchor point. In Le Fort III fractures, restoration and fixation of the arch are essential components of the repair necessary to stabilize the maxillary dentition to the cranial base. Endoscopic arch repair is a novel, technically challenging procedure that requires a different set of surgical skills and considerable training. Implementation of appropriate teaching programs and further advances in instrument development will overcome the steep learning curve associated with this technique and encourage its use.

Adult↗
PubMed2004

Alteration of amino acid residues at the L-chain N-terminus and in complementarity-determining region 3 increases affinity of a recombinant F(ab) for the human N blood group antigen.

BACKGROUND: To examine the fine specificity of glycopeptide-specific antibodies, this study focused on the human MN blood group system. F(ab) phage display methods were previously used to construct an F(ab) family in which the H-chain Fd fragment was held constant whereas the L chains were "shuffled." This yielded two related F(ab), N92 and NNA7, with low and high affinity for N, respectively. Although their L-chain sequences are very similar, sharing 92 percent amino acid identity, there are intriguing differences at the N-terminus and in complementarity-determining region 3 (CDR3) at positions 89, 91, 92, and 96. STUDY DESIGN AND METHODS: Site-directed mutagenesis, ELISA, and hemagglutination were used to examine the contributions of these variations to antibody affinity. RESULTS: Studies with the N92-S91G and NNA7-G91S mutants demonstrated that the Gly at position 91 was critically important for ensuring high affinity. Indeed, the affinity of N92-S91G was almost as high as N92TM, in which all four CDR3 residues were changed to match NNA7. N-terminal L-chain differences were surprisingly important in determining affinity. For example, when the N-terminus of N92 was changed to match that of NNA7, affinity increased approximately 30-fold. CONCLUSION: Specific residues at the L-chain N-terminus and in CDR3 significantly affected F(ab) affinity for N. Future structural studies of these F(ab), alone and complexed with this glycopeptide antigen, will provide further insights into these phenomena.

Animals↗
PubMed2002

Construction of dimeric F(ab) useful in blood group serology.

BACKGROUND: When expressed in Escherichia coli, recombinant F(ab) contain a heavy-chain Fd fragment and a complete light-chain fragment. Because these F(ab) are monovalent, their avidity is significantly lower than that of a corresponding bivalent IgG antibody. In addition, when monovalent F(ab) are used in hemagglutination assays, antiglobulin reagents are required. Therefore, it would be useful to develop a system that expresses recombinant bivalent F(ab) in E. coli. STUDY DESIGN AND METHODS: Three modified vectors were constructed. Each contained cDNA sequences encoding a peptide linked to the C terminus of a heavy-chain CH1 region: an IgG1 hinge region (Hinge), a leucine zipper (Zip), or a peptide containing the Hinge and Zip sequences in tandem (HingeZip). The vectors were used to express two cloned F(ab) recognizing human antigens M and N: NNA7 (anti-N) and 425/2B (anti-M). The recombinant proteins were expressed in E. coli and were purified and evaluated by ELISA and hemagglutination. RESULTS: By gel filtration chromatography, 35, 90, and 70 percent of the purified F(ab) expressing the Hinge, Zip, and HingeZip tails, respectively, were dimers. By ELISA, the avidity of F(ab) containing the Zip or HingeZip tails was six to eight times higher than that of the corresponding monovalent F(ab). In addition, the dimeric F(ab) directly agglutinated RBCs in concentrations similar to those of corresponding bivalent IgG antibodies. CONCLUSIONS: An introduction of dimer-inducing peptides allowed the isolation of bacterially produced, bivalent F(ab). This approach could be useful for obtaining inexpensive, serologic reagents that may replace or complement conventional MoAbs produced by mammalian tissue culture methods.

Amino Acid Sequence↗
PubMed2002

Adhesive properties of carcinoembryonic antigen glycoforms expressed in glycosylation-deficient Chinese hamster ovary cell lines.

Carcinoembryonic antigen (CEA) is an oncofoetal cell surface glycoprotein that serves as an important tumour marker for colorectal and some other carcinomas. Its immunoglobulin-like structure places CEA within the immunoglobulin superfamily. CEA functions in several biological roles including homotypic and heterotypic (with other CEA family members) cell adhesion. Cell-cell interaction can be modulated by different factors, e.g., post-translational modifications such as glycosylation. The purpose of this study was to examine whether changes in carbohydrate composition of CEA oligosaccharides can influence homotypic (CEA-CEA) interactions. In order to modulate glycosylation of CEA we used two different glycosylation mutants of Chinese hamster ovary (CHO) cells, Lec2 and Lec8. Lec2 cells should produce CEA with nonsialylated N-glycans, while Lec8 cells should yield more truncated sugar structures than Lec2. Parental CHO (Pro5) cells and the glycosylation deficient mutants were stably transfected with CEA cDNA. All three CEA glycoforms, tested in a solid-phase cell adhesion assay, showed an ability to mediate CEA-dependent cell adhesion, and no qualitative differences in the adhesion between the glycoforms were observed. Thus, it may be assumed that carbohydrates do not play a role in homotypic adhesion, and the interactions between CEA molecules depend solely on the polypeptide structure.

Animals↗