Zoltán Nyárády

Comprehensive Regression Analysis of Hepatitis B Virus X Antigen Level and Anti-HBx Antibody Titer in the Sera of Patients with HBV Infection

Although the pathogenetic significance of hepatitis B virus x protein (HBxAg) in chronic hepatitis, liver cirrhosis, and primary hepatocellular carcinoma has already been studied, the comparative analyses of both the actual serum HBxAg levels and antibody production against various HBx epitopes have been examined to lesser extent. We have simultaneously investigated the relationship between antibody production (IgG andIgM) against the HBxAg fragments and HBxAg level in the sera of patients with acute (14) or chronic hepatitis (80) and symptomless carriers (12). A recently developed sandwich-type ELISA was used for the quantitative measurements of HBxAg. Overlapping recombinant and synthetic antigens were used to map the fine epitope specificities of circulating anti-HBx antibodies. In acute hepatitis, we have found high and homogenous correlation in the IgM type immune responses against all the examined HBxAg regions. Moreover, strong correlation has been observed between IgG type immune responses to a characteristic C-terminal region (C1: 79–117) and the longest fragment (X: 10–143). Moderate correlation has been found between HBxAg concentration and the IgG type anti-HBx antibody levels against C-terminus of HBxAg in patients with chronic hepatitis. In the case of symptomless carriers, there were also demonstrable associations in the immune responses against the C-terminal sequences; however, significant correlations were found for antibody production against the N-terminal region as well. The examinations show that the C-terminal sequence, responsible for transactivation, promotes an efficient IgG antibody response in all three groups of patients, whereas the negative regulator N-terminal part of the HBxAg molecule for the most part does not trigger antibody production. This suggests that the immune responses against various — biologically active — epitopes of the HBxAg may have a different role in the pathogenesis of hepatitis and may be used as prognostic markers in human HBV infections.

Determination of the fine epitope specificity of an anti-hepatitis B virus X protein monoclonal antibody using microanalytical and molecular biological methods

The recombinant form of the 17kDa, highly hydrophobic and disulfide-bonded hepatitis B virus X protein (HBX) was used for developing a set of monoclonal antibodies (Mab). Our present goal was to determine the fine epitope specificity of our anti-HBX Mab. Based on computer analysis two sequences (amino acids 22-31 and 100-114) were predicted for possessing high immunogenity while the anti-HBX Mab did not recognized them. Limited proteolysis and mass spectroscopic analysis suggested another possible sequence (amino acids 14-26), which also proved to be negative using an immunoserological test. Subsequently, we performed a screen of a phage displayed random peptide library, by which we could localize the epitope to amino acids 88-93. This finding was confirmed using three overlapping fusion peptides spanning amino acids 77-142. Their testing in ELISA assigned the epitope to amino acids 77-95, which supports the result obtained by screening the phage displayed library. Our results suggest the necessity of a complex application of current molecular biological and immunological techniques in fine structure mapping. This approach will be useful to study the prognostic relevance of different antigenic sites on HBX during the development of chronic hepatitis and primary hepatocellular carcinoma.

Surgical closures of oropharyngocutaneous fistulas.

Of the 146 patients undergoing surgery for oropharyngeal cancer in our institution, 12 (8.2 percent) developed fistulas. As a first line of therapy, conservative measures were used, which consisted of debridement, Xeroform gauze packing, and nasogastric feeding. Seven fistulas closed after conservative treatment. Of the five patients who required surgery for fistula closure, three had large (more than 20 mm) and two had mid-size (5- to 20-mm) fistulas. In all cases, internal flaps were prepared from the healthy viable tissues surrounding the fistula, and sternocleidomastoid-trapezius-platysma myocutaneous flaps were used for external closure. None of the closures failed, and we obtained good functional and aesthetic results.

Application of Platysma-Based Transpositional Flap for Through-and-Through Facial Defect When the Facial Artery Circulation Is Blocked or Compromised

PURPOSE A novel use of site-limited platysma-based transpositional flap is demonstrated and discussed for the reconstruction of facial defects. MATERIALS AND METHODS Between January 1985 and January 2001, 342 patients were operated on for advanced oral-oropharyngeal and orofacial cancers. In 6 cases, a platysma-based transpositional flap was used for external closure of facial through-and-through defects. Internally, the saved oral mucosa was used in 4 patients and fasciocutaneous forearm free flaps in 2 patients. The facial artery was blocked in all cases. RESULTS The postoperative course was uneventful except in 1 case, when partial loss of the flap was observed intraorally. The externally used transpositional platysma-based flap showed cosmetic and functional advantages: its consistency, color, and texture were similar to those of the original facial tissues, the area of operation was the same, and the donor site was closed primarily. CONCLUSION The site-limited platysma-based myocutaneous transpositional flap is usable and safe even in those cases in which circulation of the facial artery is damaged or local vascular compromise has occurred and the facial through-and-through defect is extended. The facial reconstruction described is one of several applicable reconstructive methods that may be chosen for special facial defects. The method is not applicable when the neck is radically operated on (radical neck dissection) and/or irradiated. No similar use of platysma-based transpositional flaps has been reported thus far.

Osteoscopy for assessment of blood supply to the femoral head: a preliminary study.

Objectives The aim of our study was to develop a minimally invasive endoscopic procedure (osteoscopy), which is capable of visualizing blood supply and quantitatively assessing circulation to the femoral head at the time of definitive surgery. Methods The new diagnostic technique was developed in animal experiments (four piglets) and was subsequently tested in nine consecutive patients requiring surgery for a femoral neck fracture. The direct visualization of the femoral head circulation was performed in the mortise prepared for the implant. The osteoscope optic fiber was placed at the orifice of the cavity created by the custom-made drill bit. The “mortise-sleeve-optic” system was connected to a manometer and a saline reservoir. The bleeding from the wall of bony cavity was observed, meanwhile the inner pressure of the “mortise-sleeve-optic” system was changed gradually. The pressure measurement at the first appearance of bleeding and the intraosseal pressure was recorded. Results The animal investigations demonstrated that the osteoscopy readily distinguished among diffuse bleeding, pulsatile bleeding, and the absence of bleeding in the femoral head. The human experiments proved that a different quality of the femoral head circulation can be observed during osteoscopy. Conclusions Preliminary findings indicate that clinical osteoscopy may be a useful tool in the assessment of blood circulation to the femoral head.