Recombinant hepatitis A virus antigen: improved production and utility in diagnostic immunoassays

Hepatitis A virus (HAV) immunoassays use cell culture-derived HAV antigen to detect HAV-specific antibodies. The current method of production of HAV antigen in tissue culture is time-consuming and expensive. We previously expressed the HAV open reading frame in recombinant vaccinia viruses (rV-ORF). The recombinant HAV polyprotein was accurately processed and was assembled into subviral particles. These particles were bound by HAV-neutralizing antibodies and were able to elicit antibodies which were detected by commercial immunoassays. The present investigation compared the production of HAV antigen by standard tissue culture methods to the production of HAV antigen with the recombinant vaccinia virus system. In addition, HAV and rV-ORF antigens were assessed for their utility in diagnostic immunoassays. Serum or plasma samples from HAV antibody-positive and antibody-negative individuals were evaluated by immunoassay that used either HAV or rV-ORF antigen. All samples (86 of 86) in which HAV antibody was detected by a commercial enzyme-linked immunosorbent assay (ELISA) also tested positive by the recombinant antigen-based immunoassay (VacRIA). Similarly, all samples (50 of 50) that were HAV antibody negative also tested negative by the VacRIA. The lower limit of detection of HAV antibody was similar among immunoassays with either HAV or rV-ORF antigen. Thus, in the population studied, the sensitivity and specificity of the VacRIA were equivalent to those of the commercial ELISA. Since production of recombinant antigen is faster and less expensive than production of traditional HAV antigen, the development of diagnostic HAV antibody tests with recombinant HAV antigen appears warranted.     

Gene cloning, biochemical characterization and physiological role of a thermostable low-specificity L-threonine aldolase from Escherichia coli

BACKGROUND: This study was designed to determine the prognostic value of positive surgical resection margin or highest nodal station sampled at thoracotomy in patients with non-small cell lung cancer. METHODS: Two reviewers independently examined the surgical records and pathologic reports from a randomized trial comparing computed tomography versus mediastinoscopy for staging of lung cancer. They recorded pathologic findings at the surgical resection margin, the highest mediastinal nodal station sampled at thoracotomy, histologic type, tumor size, N status, and evidence of vascular or lymphatic invasion. These variables formed the independent variables in logistic regression models to predict recurrence. RESULTS: Except for 1 patient, follow-up at 3 years for 399 included patients was complete. Significant predictors of recurrence were tumor size (odds ratio [OR], 1.2 (per centimeter); 99% CI [confidence interval], 1.1 to 1.4), and N status (compared with N0, N1: OR, 1.6; CI, 0.8 to 3.1; N2: OR, 3.2; CI, 1.4 to 7.5). Other variables, including positive surgical resection margin, did not predict early recurrence or death. CONCLUSIONS: In patients with non-small cell lung cancer, surgical resection margin or highest nodal station sampled at thoracotomy that are involved by carcinoma do not predict recurrence. The current definition of incomplete resection has limited prognostic significance.     

Characterization of the testis and epididymis in mouse models of human Tay Sachs and Sandhoff diseases and partial determination of accumulated gangliosides

Beta-hexosaminidase (Hex) is an essential lysosomal enzyme whose activity is higher in the epididymis than in other tissues. The enzyme is also present in sperm and has been postulated to be required for fertilization. To better understand the role of Hex in reproduction, we have examined the testes and epididymides of mouse models of human Tay Sachs and Sandhoff diseases, produced by targeted disruption of the Hexa (alpha-subunit) or Hexb (beta-subunit) genes, respectively, encoding the enzymes Hex A (structure, alphabeta) and Hex B (betabeta). Testis weight, morphology, and sperm counts were unaffected in Hex-deficient mice. In the epididymis of the Hex A-deficient Hexa-/- mice, there was a large increase in the size and number of lysosomes in the initial segment/intermediate zone. In Hexb-/- mice (Hex A and B-deficient), the epididymal defects were much more extensive and the cytoplasm of all cell types throughout the efferent ducts and epididymis was filled with pale, uncondensed, enlarged lysosomes. In contrast to the brain where GM2 ganglioside accumulates, both mutant mice accumulated two non-GM2 gangliosides in the epididymis. The major accumulated species was characterized by electrospray ionization tandem mass spectrometry. The Hexa-/- male mice were fertile; however, litter sizes were reduced. The Hexb-/- males were able to sire normal sized litters up to nine weeks of age and remained healthy until 16-20 weeks of age. The extensive abnormalities in the Hexb-/- mice, in contrast to region-specific effects in the Hexa-/-mice, indicate an important and novel role for the Hex B isozyme in the epididymis and a region-specific role for Hex A in the initial segment/intermediate zone. In contrast to other reports, our results indicate that Hex is not essential for fertilization in young adult male mice. To explain the extensive epididymal abnormalities in the Hexb-/- mice, we propose that substrates for Hex, such as testis-derived glycolipids, cannot be catabolized and accumulate in lysosomes, leading to epididymal dysfunction and abnormalities in the epididymal luminal environment that supports sperm maturation.     

Colonoscopy in the management of diseases of the colon and rectum

This report covers a 2.5-year experience with colonoscopy in the management of 208 patients (104 men and 98 women, average age 58 years). Colonic bleeding of unknown cause and abnormal barium-enema findings were the most common indications for colonoscopic examination. During this period, 110 colonoscopic polypectomies were performed. Among the few complications was one case of perforation of the sigmoid from transcolonoscopic removal of a small carcinoma; the perforation was incidentally discovered at the time of subsequent laparotomy. Bleeding occurred in 6 patients, but only one of them required surgical intervention to arrest the hemorrhage. Colonoscopy is a safe, effective and reliable diagnostic and therapeutic procedure. Its use can reduce expense for the patient and obviate a long painful postoperative period.