Short communication: Where is women's cardiovascular health taught in Australian and New Zealand medical schools?

Cardiovascular disease is a major cause of mortality in women and is the leading cause of pregnancy-related mortality in Australia. This study aims to discover the extent of teaching regarding women's cardiovascular health in Australian and New Zealand medical schools. All 22 medical schools in Australia and New Zealand were approached for participation in completing this survey. Seven medical schools (32%) completed the survey and demonstrated that within our sample population, findings suggest that while women's cardiovascular health is present in medical curricula, there is a large variability in the rigour and depth as to which it is taught, as well as possible lack of explicit teaching and examination regarding this topic.

021. Current progress into testis cell transfer between cattle breeds

Male germline cell transfer has produced offspring in mice (Brinster and Zimmermann 1994). Recently the first livestock animal, a goat, was produced (Honaramooz et al. 2003), while early results in cattle are promising (Oatley et al. 2002; Izadyar et al. 2003). There is an opportunity to develop this technology for the beef industry by transferring male germ line stem cells between breeds to improve the genetics of extensive Australian beef herds. This project is a part of the CSIRO National Research Flagship program that combines expertise and facilities in divisions with complementary expertise at Monash University and the University of Sydney. The environmental constraints of Northern Australia dictate that Brahman type animals show far better survival than Bos taurus cattle, although the carcass value of Brahmans is lower than Bos taurus animals. Artificial insemination is impractical in Northern Australia and thus we aim to develop testis cell transfer technique in cattle to permit Brahman bulls to deliver semen from elite Bos taurus or composite bulls, thereby significantly increasing the growth rate, yield and meat quality of the northern beef herd. Experiments using cattle were performed to determine the applicability of techniques used in the mouse. Initial proof of concept has been achieved that germ cell transfer can result in the donor cells successfully colonizing areas of recipient testis. The viability of isolated testis cells following short term (24 h) culture has been demonstrated through transfer into recipient calves. We have completed >50 male germ cell transfers into recipient calves, using ultrasonographic guided injection into the rete testis. Success of this procedure has been demonstrated by persistence of PKH26 dyed donor cells in the seminiferous tubules of a majority of recipients >2 months after transfer. These recipient male calves have not been depleted of their endogenous spermatogonial populations and we thus expect the efficiency of the procedure to increase as depletion procedures (ongoing) are established. Concurrent with these developments has been research into large scale culture of male germ line stem cells to provide large numbers of stem cells for transplant. Culture of testis cell suspensions has demonstrated survival of enriched testis cells under varying media and culture conditions. Initial passaging of testis cell colonies has revealed mixed cell populations (immunohistochemistry positive for spermatogonia and somatic cells). Further studies will aim to demonstrate that these cultured donor cells are able to undergo spermatogenesis in the recipient animals.

107 INITIAL RESULTS FROM MALE GERM CELL TRANSFER BETWEEN CATTLE BREEDS

Male germline cell transfer has produced offspring in mice (Brinster & Zimmerman 1994 PNAS 91, 11 298–11 302). Recently the first livestock animal, a goat, was produced (Honaramooz et al. 2003 Mol. Reprod. Dev. 64 422–64 428.), and early results in cattle are promising (Izadyar et al. 2003 Reproduction 126, 765–774; Oatley et al. 2002 J. Anim. Sci. 80, 1925–1931). We have assessed the outcome of male germ cell transfer between breeds of cattle and the efficacy of two vital dyes as markers of donor cells following transfer. Testis cells from three Bos taurus (Angus) bull calves were used as donor cells to transfer into six Bos indicus cross (predominantly Brahman bloodline) bull calves. Each of the calves was prepubertal and aged between 5 and 7 months. The calves were castrated; then a single-cell suspension of testis cells was prepared enzymatically using collagenase, DNAase, and trypsin. Prior to transfer into the recipient calves, the testis cell suspensions were dyed with one of two long-term vital dyes (PKH26 or CFDA). Approximately 300 million cells were injected into the rete of each testis under ultrasonographic guidance. In four of the six recipients, CFDA was injected into one testis and PKH26 into the other. These four recipients were castrated at 2, 4, 6, and 8 weeks after transfer. The other two recipients received either CFDA or PKH26 into both testes and were castrated at 8 weeks after transfer. Following castration, PKH positive donor cells were found in freshly isolated tubules of each of the five recipients that received PKH-dyed cells, while no CFDA-positive donor cells were conclusively identified in any of the recipients. In the freshly isolated tubules, clumps of PKH-positive donor cells were observed, which indicated either cell division or substantial local colonization of certain areas of the tubules. Frozen sections were used to further localize the PKH positive donor cells. Positive cells were located on the seminiferous tubule basement membrane, which indicates these cells had successfully migrated from the tubule lumen and were likely to be spermatogonia. There was variation in the amount of fluorescence for individual cells, which indicated either cell division or variable uptake of the stain during the staining procedure. We were disappointed to find no conclusive evidence of CFDA stained cells as we encountered high background fluorescence from the majority of testis cells. Although this fluorescence was quenched within 10 s, we were unable to find positive cells with any certainty. We have concluded that PKH26 was more suitable for labeling donor testis cells and that donor cells can be identified for at least 2 months following transfer. Each of the recipients that received PKH26 stained cells retained these cells in the tubule epithelium, which suggests that transfer between different animals, and indeed between breeds, can be achieved. Further studies will aim to demonstrate that donor cells are able to undergo spermatogenesis in the recipient animals.

269. Optimal testicular size of donor and recipient for testicular germ cell transplantation in the bovine

The maturity status of donor and recipient testis appears to be important in the efficiency of testicular germ cell transplantation. When neonatal mice were used as recipients, they show 9.4 times greater colonization and 4 times larger colony size than in the adult.1 The objective of this study in cattle was to investigate the effect of testicular maturity of donor and recipient calves on success of the testis cell transplant procedure. Testicular maturity was measured indirectly by scrotal circumference and donor testicular cells were enzymatically isolated from 8 Angus calves aged 5–7 months (scrotal circumference, SC of 18–22cm) and injected into both testes of 12 recipient calves aged 4–6 months (SC 15–21cm. Donor cells were labeled with the red fluorescent dye PKH26 then transferred into the rete testis under ultrasonographic guidance. Castration of recipients was performed 2–6 months following injection and then frozen sections were used to localize the PKH26 positive donor cells. Five sections from different 5 areas in each testis were prepared and 100 tubules were counted. In 15 of the 24 (63%) testes, PKH positive donor cells were identified. There was no correlation between colonization rate and maturity of donor animal testis for the range of testis sizes studied. Testis cells from donors of SC 18-20 cm or of SC 21-22 did not result in different number of recipient testis with positive cells (7/10 (70%) v. 8/14 (57%)) or the number of positive cells per testis (1.92 ± 0.67% v. 2.5 ± 1.01%). Recipient maturity (SC of 15–18 cm v. SC of 19–21 cm) had no effect on the colonization rate (7/11 (64%) v. 8/13 (62%)); however, there were significantly more positive cells per testis in less mature (SC of 15–18) recipients (3.18±1.21% v. 1.52 ± 0.64% P < 0.05)). In summary we have demonstrated successful testicular germ cell transplantation between calves and while donor testis cell age appeared to have little effect on the efficiency of colonization, less mature testis provided more suitable conditions for colonization. (1)Shinohara T, Orwig KE, Avarbock MR and Brinster RL. (2001) Remodeling of the postnatal mouse testis is accompanied by dramatic changes in stem cell number and niche accessibility. PNAS 98(11), 6186–6191.

A possible contributory role of BK virus infection in neuroblastoma development

The tumor suppressor protein p53 is aberrantly localized to the cytoplasm of neuroblastoma cells, compromising the suppressor function of this protein. Such tumors are experimentally induced in transgenic mice expressing the large tumor (T) antigen of polyomaviruses. The oncogenic mechanisms of T antigen include complex formation with, and inactivation of, the tumor suppressor protein p53. Samples from 18 human neuroblastomas and five normal human adrenal glands were examined. BK virus DNA was detected in all neuroblastomas and none of five normal adrenal glands by PCR. Using DNA in situ hybridization, polyomaviral DNA was found in the tumor cells of 17 of 18 neuroblastomas, but in none of five adrenal medullas. Expression of the large T antigen was detected in the tumor cells of 16 of 18 neuroblastomas, but in none of the five adrenal medullas. By double immunostaining BK virus T antigen and p53 was colocalized to the cytoplasm of the tumor cells. Immunoprecipitation revealed binding between the two proteins. The presence and expression of BK virus in neuroblastomas, but not in normal adrenal medulla, and colocalization and binding to p53, suggest that this virus may play a contributory role in the development of this neoplasm.