In situ normothermic regional perfusion for controlled donation after circulatory death--the United Kingdom experience.

Organs recovered from donors after circulatory death (DCD) suffer warm ischemia before cold storage which may prejudice graft survival and result in a greater risk of complications after transplant. A period of normothermic regional perfusion (NRP) in the donor may reverse these effects and improve organ function. Twenty-one NRP retrievals from Maastricht category III DCD donors were performed at three UK centers. NRP was established postasystole via aortic and caval cannulation and maintained for 2 h. Blood gases and biochemistry were monitored to assess organ function. Sixty-three organs were recovered. Forty-nine patients were transplanted. The median time from asystole to NRP was 16 min (range 10-23 min). Thirty-two patients received a kidney transplant. The median cold ischemia time was 12 h 30 min (range 5 h 25 min-18 h 22 min). The median creatinine at 3 and 12 months was 107 µmol/L (range 72-222) and 121 µmol/L (range 63-157), respectively. Thirteen (40%) recipients had delayed graft function and four lost the grafts. Eleven patients received a liver transplant. The first week median peak ALT was 389 IU/L (range 58-3043). One patient had primary nonfunction. Two combined pancreas-kidney transplants, one islet transplant and three double lung transplants were performed with primary function. NRP in DCD donation facilitates organ recovery and may improve short-term outcomes.

Clinical audit; who is auditing who?

Clinical audit is the principal means by which current clinical practice is improved. Doctors in training must gain positive experience of audit as juniors, so as to establish the importance of audit for future practice. Good audit requires involvement of doctors in training, a high level of participation and a leading role to be taken by the professional bodies. To examine the degree to which such criteria are met currently, the quality and prevalence of clinical audit, the participation of junior doctors in audit, and the preparedness of medical professional bodies' to guide audit were assessed. One hundred and twenty-six junior and senior house officers in three Edinburgh hospitals were administered questionnaires in person, whilst eight Royal Colleges, the British medical Association and the General Medical Council were assessed by the quality of their written guidelines for audit. The data showed that only thirteen out of twenty four specialties, which employed half the juniors, utilised clinical audit. Half of these audit programs were structured to lead to improved patient care. Surprisingly, only three out of ten professional bodies were able to provide good quality audit information. In conclusion, clinical audit is not universal practice and many existing audit programs are inappropriately structured. Commonly, doctors at all levels seemed unaware of the goals of clinical audit. In addition, the majority of professional bodies provide poor information, thereby impeding successful audit by doctors in training. Clinical audit will not succeed until such deficiencies are rectified.

Modulation of arginine vasopressin secretion from cultured ovine hypothalamic cells by glucocorticoids and opioid peptides.

In sheep, arginine vasopressin (AVP) appears to be a more potent ACTH-releasing factor than ovine corticotrophin-releasing hormone. In order to investigate the neuroendocrine regulation of AVP secretion we have developed a novel system for maintaining fetal ovine hypothalamic neurones in serum-free culture. Hypothalamic neurones derived from fetal sheep at day 70 gestation (term = 145 days) secreted AVP under basal conditions and in response to repeated potassium-induced depolarizations, for up to 35 days in vitro. AVP secretion was time- and calcium-dependent. AVP secreted from ovine hypothalamic cells co-eluted with synthetic AVP on a Sephadex chromatography column and diluted in parallel with AVP standard in the radioimmunoassay. The addition of cortisol (150 nM) to medium bathing ovine hypothalamic cells significantly inhibited basal, and potassium-induced AVP secretion without altering the AVP content of the cell cultures. Furthermore, the opioid peptide [D-Pro10]Dynorphin(1-11) which acts via the kappa opioid receptor, significantly inhibited basal and potassium-stimulated AVP secretion, an effect which was abolished when cells were cultured in the presence of cortisol. These data show that hypothalamic AVP is a site for negative feedback regulation within the ovine hypothalamic-pituitary-adrenal axis. Furthermore, these data suggest that the kappa opioid system inhibits AVP secretion from ovine hypothalamic neurones, a response which is modulated by glucocorticoids.

Corticotrophin-releasing factors in the hypothalamus of the developing fetal sheep.

Corticotrophin-releasing hormone (CRH) and arginine vasopressin (AVP) are secreted from the hypothalamic median eminence to elicit the secretion of ACTH from the pituitary corticotrophs. During fetal development there is progressive maturation of the hypothalamic-pituitary-adrenal axis, manifest as increasing plasma ACTH and cortisol concentrations, which in species such as sheep culminates in the onset of birth. However, the precise nature of the hypothalamic signal controlling fetal pituitary ACTH secretion remains poorly understood. To investigate the ontogeny of this hypothalamic signal, the present study examined immunoreactive and bioactive ACTH-releasing factors in the developing fetal sheep hypothalamus. Immunoreactive CRH and AVP were measured by radioimmunoassay in extracts of hypothalami taken at day 70, day 100, and day 130 gestation (term = 145 days). There was a progressive and significant (P < 0.01) increase in hypothalamic CRH and AVP concentrations which was particularly marked between d100 and d130 gestation. AVP was always present in higher concentrations that CRH, although this difference was significantly reduced by day 130 gestation as the result of a large increase in the content of CRH relative to AVP. Sephadex G50 chromatography revealed that immunoreactive CRH and AVP in hypothalamic extracts existed as single molecular forms corresponding to synthetic peptides at each gestational age. In addition, these immunoreactive forms of CRH and AVP possessed significant ACTH-releasing bioactivity as measured in primary cultures of adult sheep anterior pituitary cells. Furthermore, significant bioactivity was present in high and low molecular weight fractions eluted after chromatography which did not contain any CRH or AVP immunoreactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuroendocrine regulation of sheep fetuses.

During fetal development the neuroendocrine system plays a pivotal role in the regulation of normal intrauterine development, growth and differentiation and the onset of birth. Studies on the ontogenic development of neuroendocrine function in sheep fetuses are discussed with particular reference to the differential regulation of the pituitary-gonadal and pituitary-adrenal axis. Fetal pituitary-gonadal activity increases to a maximum at mid-gestation and is suppressed just before birth. Using immunocytochemistry, we have examined the ontogeny of gonadotroph development in the pituitary of female sheep fetuses. At day 70 of gestation (term = 145 days) only immunopositive luteinizing hormone beta (LH beta) cells were present. The number and intensity of staining of these LH beta cells increased by day 100 and declined again by day 130. Immunopositive alpha-subunit and follicle-stimulating hormone beta (FSH beta) cells appeared by day 100 of gestation and had further increased in number and staining intensity by day 130. Treatment of fetuses with the gonadotrophin-releasing hormone (GnRH) agonist, buserelin, from day 70 of gestation results in desensitization of the fetal pituitary gonadotrophs, suppression of pituitary gonadotrophin mRNA and a reduction in the number of immunopositive gonadotrophin-containing cells. Thus, in sheep fetuses the development of cells containing LH and FSH depends critically on an appropriate GnRH signal from the fetal hypothalamus. In contrast, hypothalamo-pituitary-adrenal activity increases during gestation to reach a maximum before birth. This is characterized by a progressive increase in fetal plasma adrenocorticotrophic hormone (ACTH) and cortisol concentrations, and a high frequency of ACTH and cortisol pulses in the final hours before parturition. Steady state concentrations of pro-opiomelanocortin (POMC) mRNA increase throughout fetal development but decline dramatically in the final days before birth, when ACTH concentrations are at a maximum. This decline in POMC expression is probably the result of the negative feedback effects of high cortisol concentrations. The neuroendocrine mechanisms that mediate the pulsatile secretion of ACTH at this crucial time are complex and as yet incompletely defined. However, the opioid antagonist, naloxone, suppresses the secretion of ACTH during the final days before birth, thus providing evidence for the tonic regulation of ACTH secretion by stimulatory endogenous opioids. Prostaglandins that are secreted from the placenta during late gestation stimulate fetal ACTH, but not gonadotrophin secretion, whereas placental steroids are thought to inhibit fetal gonadotrophin secretion.(ABSTRACT TRUNCATED AT 400 WORDS)