Growth of preimplantation embryos is influenced byThe cells of the mammalian preimplantation embryo (from the time of fertilization until the implantation of the blastocyst into the uterus) form the progenitor cells for all other cell lineages. The regulation of the growth and survival of the cells of the early embryo is, however, poorly understood. Mammalian preimplantation embryos develop in vitro with simple medium requirements and have no absolute requirement for exogenous vitamins, hormones, or growth factors. This contrasts with the absolute requirement of normal somatic cells for exogenous mitogens and survival factors. The continued mitoses of preimplantation embryo cells in the absence of exogenous growth factors implicates a role for endogenous, autocrine trophic factors, or the constitutive activation of signaling pathways in the early embryo. Several lines of evidence support a role for the former: (i) the rate of embryo development in vitro is density-dependent, with embryos growing in relatively small volumes (or in large groups) developing more successfully than those grown in large volumes (or individually) (1, 2); (ii) the synthesis by the preimplantation embryo of a number of growth factor ligands and their receptors (3-8); and (iii) the capacity of some exogenous growth factors to enhance embryo metabolism in vitro and to compensate for the adverse effects of culture in large medium volumes (1, 2, 9).Experimental partial deprivation of released autocrine trophic factors did not arrest the cell-cycle at given checkpoints (9). Rather, there was progressive loss of viability with increased cell death as embryos progressed past the 8-cell stage. This finding suggests that the autocrine factors may act as survival factors rather than classical growth factors (triggering progression through specific cell-cycle checkpoints). While several autocrine factors have been implicated, platelet-activating factor (PAF) 1 seems to be one of the first produced, being synthesized de novo by the embryo soon after fertilization (10, 11). Its actions are required by the mid-2-cell stage for normal rates of embryo survival (9).Despite this range of supportive data, there is limited direct evidence for the action of autocrine trophic factors in early embryo development. Transgenic and recombinant knock-out models have not generally been informative of the growth requirements of the early embryo prior to implantation. This may be due to extensive redundancy of regulatory pathways.
Homicide-suicide forms a distinct form of homicide. An analysis of cases in the Yorkshire and Humberside region of England between 1991 and 2005 revealed 37 episodes with 42 victims. Previous studies have shown a high rate of use of firearms. Over the last 2 decades firearms legislation has become more restrictive. In this study all assailants were male, mean age 46.8 years. The commonest method of homicide was strangulation (36%) with 16% killed by firearms. This is a reduction compared with a previous study in the same region. All killers who shot their victims killed themselves with firearms. There were no multiple killings with firearms in this study and no stranger killings. Hanging was the commonest method of suicide. During the same period the use of firearms as a method of homicide increased in England and Wales with handguns, the most common weapon. Nationally, suicide after homicide has remained at a similar rate over the half century and is an uncommon phenomenon. Firearms use remains low in both homicide and homicide-suicide episodes in England, and further analysis is required to determine changes in patterns of killing.
26 December 2004 is a date that changed the lives of incalculable numbers of persons the world over as a result of the Asian tsunami. Krabi Province was one of the more severely affected areas of Thailand, with many of the dead and injured being non-Thai, persons who were holidaying during the peak tourist season. Some injury types were comparatively underrepresented, such as head, thoracic and abdominal trauma. Does the classic trimodal distribution of death following injury help explain the types of injuries seen in the survivors of the disaster? Data are incomplete at this point in time, but with time it may be found that the trimodal model displays the pattern of death in mass casualty disaster situations. This may aid in the development of specific strategies to deal with similar events in the future.
The date 26 December 2004 saw a massive tidal wave propagated from a 9.0 Richter scale suboceanic earthquake off the coast of Sumatra in South-East Asia. It swept across the Indian Ocean over a matter of hours leaving destruction in its wake. In Southern Thailand, Krabi Hospital, that province's major tertiary health centre, received the majority of the region's tsunami victims. Well-rehearsed contingency plans were in place to cope with 10, 20 and 40 trauma victims in the case of an extreme event. By the end of 26 December some 500 injured people had been treated at Krabi Hospital: well in excess of the 'worst case scenario' planning. Over the following days a total of 1357 tsunami victims were treated. Over the course of the day victims were able to move through the hospitals' system and gain appropriate treatment. This was achieved through the almost superhuman dedication of the hospitals' well-trained nursing and medical staff. In addition to this were large numbers of both Thai and foreign volunteers, who aided people with basic necessities such as providing them with food, water and clothing as well as simple human comfort, some also acting as translators for the health-care workers and the masses of injured and displaced people. Makeshift wards were constructed in halls and little used areas of the hospital, using army style stretchers to accommodate the wounded. Even though the disaster contingency plans at Krabi Hospital were utterly overrun, the fact that well-thought out and practised strategies were in place saved incalculable lives. The message is clear: practised responses to mass trauma situations will save lives and allows health-care teams to coordinate well in the face of overwhelming odds without panic. All centres should routinely practise disaster response through scenario-based training.
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