Biomedical subjects
P A Bloxham
Publications and source records attributed to P A Bloxham.
Unreliable diagnosis of Haemobartonella felis.
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Haemorrhagic syndrome of cattle associated with the feeding of sweet vernal (Anthoxanthum odoratum) hay containing dicoumarol.
An outbreak of a haemorrhagic diathesis in cattle fed home produced hay is described. A similar syndrome was reproduced experimentally in calves by feeding them the hay. The experimental disease was characterised by increased prothrombin and partial thromboplastin times while the leucocyte and erythrocyte counts remained normal until the terminal haemorrhage. The calves ate well and grew well until the rapid onset of progressive weakness, stiff gait, mucosal pallor, tachycardia, tachypnoea and haematomata ending in sudden death. The absence of blood coagulation was seen at necropsy while petechial, ecchymotic and free haemorrhages were found in most organs. Particularly striking were massive ecchymotic haemorrhages on the peritoneal surface of the rumen, a bloody, gelatinous mass enveloping each kidney and extensive bruising, haemorrhage and haematomata in the subcutis of the limbs. In a second feeding trial the effects of various preparations of vitamin K1 and vitamin K3 were investigated. Oral administration of large quantities of vitamin K1 reduced the elevated prothrombin time; vitamin K3 acted less consistently. Analysis of the hay for trichothecene mycotoxins was negative but floral analysis revealed that sweet vernal grass (Anthoxanthum odoratum) comprised about 80 per cent of the hay. Dicoumarol was detected in the hay and in the serum and ruminal contents of the experimental calves. The diagnosis, treatment, control and importance of this syndrome in the United Kingdom are discussed.
A bovine herd fertility scheme.
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Selenium status of cattle in Devon.
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Ovine enzootic abortion diagnosis.
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A Canadian commercial ovum transfer unit.
Mr. Bloxham received support from the Harry Steele-Bodger Memorial Fund towards the expenses of working at the Medical School of the University of Calgary, Alberta, Canada, where he was able to continue his researches on early implantation of mammalian blastocysts. He also took the opportunity to visit the commercial ovum transfer unit near the University of Calgary and has provided the following impressions of that part of his stay in Canada.
Tamoxifen inhibition of an in vitro oestradiol-induced surface coat change on mouse blastocysts.
1. Eighty-nine hour post-coitus mouse blastocysts cultured in the presence of oestradiol-17beta underwent a histochemically detectable surface coat change. 2. Tamoxifen was found to inhibit this in vitro-induced change. The role of Tamoxifen as an inhibitor of implantation is discussed.
Abolition of the pre-implantation surge of plasma oestrogens in mice with tamoxifen.
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An effect of Tamoxifen (I.C.I. 46,474) on the surface coat of the late preimplantation mouse blastocyst.
The oral adminitration of Tamoxifen on Days 2,3 and 4 after mating, or on Day 2 only, was found to prevent the oestrogen-dependent surface-coat change of the late preimplantation blastocyst in the mouse. It is suggested that his is an antioestrogenic manifestation and that ist is, at least in part, responsible for the drug's known antifertility effect.
From ovulation to blastocyst attachment. A review of early embryonic life in the mouse.
The development of the blastocyst from ovulation to implantation is discussed with particular reference to control mechanisms that enable the embryo to attach to the uterine wall, using the mouse as a laboratory model. The physical and chemical changes in the uterus and within the blastocyst are seen as essential steps towards implantation. Evidence that the oestrogen plays a fundamental part in the overall control of these changes is demonstrated. The interrelationship between the hormones of early pregnancy and the uterine production of histamine and cycle AMP is viewed in conjunction with the development of the blastocyst and the decidual changes that occur in the uterus which are essential for nidation.