Food Poisoning - A Major Threat to Airline Operations

In the spring of 1984, British Airways was involved in a majorfood poisoning outbreak which affected nearly 1000 passengers,aircrew and ground personnel. The operational impact was worldwideand could have resulted in the cessation of the airline's day-to-dayoperations. The investigation paralleled a major aircraft disaster in thenumber of national and international agencies involved and inthe variety of disciplines engaged. Although the causative organismwas rapidly identified (salmonella), and its introduction intothe food chain proved to be a key factor, the scale of the outbreakwas the result of an interaction of other factors. As with amajor aircraft accident, none of the factors alone would havecaused the near disaster that occurred. Requests for reprints should be addressed to: Dr Frank S. Preston OBE, 2 Ravensmead, Chalfont St Peter, Bucks SL9 0NB, UK     

The cryopreservation of donor semen by a simplified method: use in an IVF and GIFT programme

The cryopreservation of semen used in assisted reproduction procedures was carried out exclusively by a simplified method in which a mixture of semen and cryoprotectant was contained in 1-ml tuberculin syringes and plunged directly into liquid nitrogen. Donor semen samples halved and frozen in syringes and in straws in a controlled-rate freezer showed no significant difference in post-thaw motility (P = 0.217) or survival (P = 0.217) after 30 min. However, after 180 min the survival rate showed a significant reduction in syringes (P = 0.045). A significant difference (P less than 0.00008) in the rate of fertilization of oocytes was seen in IVF cycles using frozen-thawed donor sperm (58/142, 42%) when compared to fresh sperm from husbands (2315/3926, 59%). A significant reduction (P less than 0.00005) in fertilization rate was also observed in the case of supernumerary oocytes in GIFT cycles with the cryopreserved donor sperm (29/132, 22%) compared to the husbands' sperm (239/514, 46%). However, the pregnancy rate following IVF and embryo replacement was the same after fertilization with fresh sperm (75/351, 21%) as opposed to frozen sperm (3/14, 21%). Furthermore, a higher pregnancy rate was observed in GIFT with frozen donor sperm (9/19, 47%) than with fresh sperm from husbands (28/103, 27%), though this was not statistically significant (P = 0.079). These results show this simplified methods of semen cryopreservation to be effective when used in an IVF and GIFT programme, giving pregnancy rates comparable to fresh normospermic semen samples. The method is simple, quick and inexpensive.     

Fertilization of human oocytes in vitro by spermatozoa from oligozoospermic and normospermic men

Sperm were isolated from the semen of oligozoospermic (less than 20 x 10(6) sperm/ml) and normospermic (greater than or equal to 20 x 10(6) sperm/ml) men in an in-vitro fertilization (IVF) programme. Oocytes from the female partners were inseminated with either 75 or 100 x 10(3) motile sperm and checked for fertilization after 16-20 h. A significant reduction in the overall fertilization rate of oocytes was seen for the oligozoospermic group compared to the normospermic group, at both insemination concentrations. In the oligozoospermic group, a fertilization rate of 31% (19/61) was achieved when oocytes were inseminated with 75 x 10(3) sperm, and 38% (9/24) when inseminated with 100 x 10(3) sperm. This compared with rates of 57% (397/696) and 64% (650/1018), respectively, for normospermic cases at both insemination concentrations. No evidence of fertilization was seen in 36% (4/11) and 67% (4/6) of oligozoospermic cases when 75 or 100 x 10(3) sperm were used, compared with values of 13% (17/133) and 9% (20/212), respectively, in normospermic cases. After excluding zero cases, the fertilization rate of oocytes for the oligozoospermic group (75%; 9/12) was similar to the normospermic group (70% 650/935) when 100 x 10(3) sperm were used. However, when 75 x 10(3) sperm were used, the fertilization rate for the oligozoospermic group (41%; 19/46) was significantly lower than that of the normospermic group (62%; 397/645). Following the transfer of embryos into the female partner, clinical pregnancies were diagnosed in 2/7 (29%) oligozoospermic cases and 27/267 (10%) normospermic cases.(ABSTRACT TRUNCATED AT 250 WORDS)