BAX System Research Articles

Expression of Bcl-2 and Bax in the human corpus luteum during the menstrual cycle and in early pregnancy: regulation by human chorionic gonadotropin.

To investigate the relationship between apoptosis and the Bcl-2/ Bax system in the human corpus luteum (CL), the frequency of apoptosis and expression of Bcl-2 and Bax were examined in the CL during the menstrual cycle and in early pregnancy. In situ analysis of DNA fragmentation showed that the number of apoptotic cells was much greater in the regressing CL than that in the midluteal phase CL, whereas there were almost no apoptotic cells in the CL of early pregnancy. Immunohistochemistry revealed that Bcl-2 expression was observed in the luteal cells in the midluteal phase and early pregnancy, but not in the regressing CL. In contrast, Bax immunostaining was observed in the regressing CL, but not in the midluteal phase and early pregnancy. bcl-2 messenger ribonucleic acid (mRNA) levels in the CL during the menstrual cycle were highest in the midluteal phase and lowest in the regressing CL. In the CL of early pregnancy, bcl-2 mRNA levels were significantly higher than those in the midluteal phase. In contrast, bax mRNA levels were highest in the regressing CL and remarkably low in the CL of early pregnancy. Western blot analyses revealed that Bcl-2 expression was significantly lower in the regressing CL than in the midluteal phase and early pregnancy, and that Bax expression was, in contrast, significantly higher in the regressing CL than in the midluteal phase and was remarkably low in the CL of early pregnancy. When corpora lutea of the midluteal phase were incubated with hCG, hCG significantly increased the mRNA and protein levels of Bcl-2 and significantly decreased those of Bax. In conclusion, Bcl-2 and Bax may play important roles in the regulation of the life span of the human CL by controlling the rate of apoptosis. hCG may act to prolong the life span of the CL by increasing Bcl-2 expression and decreasing Bax expression when pregnancy occurs.

Sensitivity and Specificity of the Test Kit BAX® for Screening/ E. coli O157:H7 in Ground Beef: Independent Laboratory Study

An independent laboratory study of the BAX for Screening/E. coli O157:H7 kit was conducted at the National Food Laboratory, Inc., Dublin, CA, to complete AOAC Performance Tested Method certification. The BAX system kit was compared with the BAM culture method and a modified BAM culture method for detection of E. coli O157:H7 in ground beef. The BAX system kit detected the target organism at levels approximately 10-fold lower than those that gave positive BAM results. This study validated product claims, and Performance Tested Method status was granted.

Application of the BAX for Screening/Genus Listeria Polymerase Chain Reaction System for Monitoring Listeria Species in Cold-Smoked Fish and in the Smoked Fish Processing Environment

The cold-smoked fish industry was used as a model for the development of a system for monitoring Listeria spp. in foods and in the food processing environment. A total of 214 samples including raw fish, fish during the cold-smoking process, finished product, and environmental samples were collected from three processing facilities over two visits to each facility. Samples were screened for Listeria spp. using the BAX for Screening/genus Listeria polymerase chain reaction system (PCR) and by culture. Listeria spp., confirmed by the API Listeria test strip or by a PCR assay targeting the L. monocytogeneshlyA gene, were isolated from a total of 89 (41.6%) samples. Of these, 80 samples also tested positive for Listeria spp. using the BAX system. Specifically, 42 (55.3%) environmental samples (n = 76), 11 (25.6%) raw materials samples (n = 43), 20 (35.1%) samples from fish in various stages of processing (n = 57), and 7 (18.4%) finished product samples (n = 38) tested positive for Listeria spp. using the BAX system. Five (4.0%) of the 125 culture-negative samples yielded BAX system-positive results. Listeria isolates from each of nine culture-positive/BAX system-negative samples yielded a positive reaction when tested in pure culture by the BAX system, suggesting that our false-negative results were likely due to the presence of low Listeria numbers in the initial enrichment as opposed to nonreacting isolates. The employment of alternative enrichment protocols, such as the two-step enrichment recommended by the manufacturer, may increase the sensitivity of the assay.

Reciprocal changes in the expression of Bcl-2 and Bax in hypoglossal nucleus after axotomy in adult rats: possible involvement in the induction of neuronal cell death

Numerous studies of neonatal neuronal development in mammals have revealed that neuronal cell death following axotomy is apoptotic in nature. In adult animals, however, neuronal cell death following axonal injury may or may not exhibit features of apoptosis. Bcl-2 and Bax have been identified as inhibitor and promoter proteins, respectively, of apoptosis. To investigate the relationship between these proteins and neuronal cell death following axotomy in adult animals, we performed axotomy of the right hypoglossal nerve in adult male Wistar rats, and sacrificed the rats at various intervals after axotomy. We analyzed the expression of Bcl-2 and Bax immunohistochemically in the hypoglossal nuclei of the adult rats following axotomy. Our analysis showed an increase in the percentage of Bax-positive motoneurons relative to the total number of motoneurons in the hypoglossal nucleus on the axotomy side at three days after axotomy. In contrast, a low percentage of Bcl-2-positive motoneurons to the total number of motoneurons was noted at the same time interval after axotomy. Quantitative analysis of the signal intensity for Bcl-2 and Bax in individual neurons showed that Bax immunostaining significantly increased 7 days after axotomy, while the intensity of Bcl-2 immunostaining decreased in most of Bcl-2-positive neurons. Our results confirmed the occurrence of motoneuron cell death in adult rats after axotomy, and that a close temporal relationship exists between the reciprocal changes in Bcl-2/Bax expression and the loss of motoneurons. These results indicate the possible involvement of the Bcl-2/Bax system in the induction of neuronal cell apoptosis after axotomy in adult rats.

Performance Tested Method Certification of BAX™ for Screening/Salmonella: A Case Study

This report details the independent laboratory study of the BAX for Screening/Salmonella assay to complete AOAC Performance Tested Method certification. The performance of the BAX system was compared with those of BAM culture methods on food samples inoculated with Salmonella. This study validated product claims. Performance Tested Method status was granted for the screening assay.

Detection of Salmonella Cells within 24 to 26 Hours in Poultry Samples with the Polymerase Chain Reaction BAX System

BAX, a commercial polymerase chain reaction-based system, was evaluated to determine the efficacy of the system with different concentrations of Salmonella cells in mixed cultures and compared to conventional methods for detection of inoculated Salmonella cells from poultry samples. When present in enrichment broths at levels of 105, 104, and 103 CFU/ml, Salmonella cells were detected in 100, 93, and 41% of samples, respectively. Salmonella cells were detected in 23 of 150 (15%) processed chicken rinse samples with the BAX system compared to 18 of 150 (12%) samples with conventional methods. Salmonella cells were detected in 28 of 50 (56%) ground turkey samples with the BAX system compared to 25 of 50 (50%) samples with conventional methods. Overall there was a 97% method agreement. One false-negative and two false-positive results were obtained with the BAX. Band sizes and intensity of the polymerase chain reaction product were shown to be correlated with estimated numbers of Salmonella CFU present in the enriched and inoculated samples. The assay was able to detect 104Salmonella CFU/ml of enrichment medium, which allows consistent detection of Salmonella cells within 24 to 26 h. The high degree of sensitivity and specificity of the BAX system make it a reliable alternative to conventional bacterial cultural methods.

Specificity of the BAX Polymerase Chain Reaction System for Detection of the Foodborne Pathogen Listeria monocytogenes

The polymerase chain reaction (PCR) can be used for rapid and specific detection of foodborne pathogens. One commercial kit, the Qualicon BAX system uses PCR to detect Listeria monocytogenes in enrichment cultures derived from food and environmental samples. The specificity and sensitivity of the BAX system for detecting L. monocytogenes were characterized by using both pure and mixed cell cultures, and optimal conditions for production of cell lysates were determined. The BAX system was highly specific for L. monocytogenes, and no interference was seen in the presence of either other Listeria species or microbes from other genera. The assay detected L. monocytogenes at 10(5)-10(6) colony-forming units/mL. This sensitivity is adequate for detecting viable cells after enrichment but prevents false-positive signals from nonviable cells.

Human chorionic gonadotropin (hCG) inhibits cisplatin-induced apoptosis in ovarian cancer cells: possible role of up-regulation of insulin-like growth factor-1 by hCG.

Gonadotropins have been suggested to play a role in the development or progression of ovarian cancer, and we have previously reported the expression of luteinizing hormone/ human chorionic gonadotropin (LH/hCG) receptor in 40% of epithelial ovarian carcinomas. To examine the biological effect of LH/hCG on ovarian cancer cells, apoptosis induced by cisplatin with or without hCG treatment was investigated in 2 ovarian cancer cell lines, OVCAR-3 and SK-OV-3. Stimulation of cell proliferation by hCG was also studied. In addition, to analyze further the mechanism of hCG signaling involved in apoptosis-inhibition, we examined the expression of LH/hCG receptors and the regulation by hCG for apoptosis-inhibitory pathways, such as the bcl-2/bax system and the insulin-like growth factor-1 (IGF-1)/IGF-1 receptor (IGFR) system. hCG did not increase cell proliferation in either cell line. However, hCG treatment suppressed cisplatin-induced apoptosis by 58% in the OVCAR-3 cells, as shown by immunofluorescent staining and quantitation of DNA fragmentation. LH/hCG receptor mRNA was expressed only in OVCAR-3, and no apoptosis-inhibitory effect of hCG was observed in the SK-OV-3 cells that did not express the receptor. In the OVCAR-3 cells, hCG significantly increased mRNA expression of IGF-1, but did not change mRNA levels of bcl-2/bax. Our findings suggest that LH/hCG influences the chemosensitivity of ovarian cancer cells through an apoptosis-inhibitory signal possibly via up-regulation of IGF-1 expression.