Pregnancy-induced adaptation in the neuroendocrine control of prolactin secretion

During pregnancy, neuroendocrine control of prolactin secretion is markedly altered to allow a state of hyperprolactinaemia to develop. Prolactin secretion is normally tightly regulated by a short-loop negative-feedback mechanism, whereby prolactin stimulates activity of tuberoinfundibular dopamine (TIDA) neurones to increase dopamine secretion into the pituitary portal blood. Dopamine inhibits prolactin secretion, thus reducing prolactin concentrations in the circulation back to the normal low level. Activation of this feedback secretion by placental lactogen during pregnancy maintains relatively low levels of prolactin secretion during early and mid-pregnancy. Despite the continued presence of placental lactogen, however, dopamine secretion from TIDA neurones is reduced during late pregnancy. Moreover, the neurones become completely unresponsive to endogenous or exogenous prolactin at this time, allowing a large nocturnal surge of prolactin to occur from the maternal pituitary gland during the night before parturition. In this review, we describe the changing patterns of prolactin secretion during pregnancy in the rat, and discuss the neuroendocrine mechanisms controlling these changes. The loss of response to prolactin is an important maternal adaptation to pregnancy, allowing the prolonged period of hyperprolactinaemia required for mammary gland development and function and for maternal behaviour immediately after parturition, and possibly also contributing to a range of other adaptive responses in the mother.     

Graduates of different UK medical schools show substantial differences in performance on MRCP(UK) Part 1, Part 2 and PACES examinations

Background  

The UK General Medical Council has emphasized the lack of evidence on whether graduates from different UK medical schools perform differently in their clinical careers. Here we assess the performance of UK graduates who have taken MRCP(UK) Part 1 and Part 2, which are multiple-choice assessments, and PACES, an assessment using real and simulated patients of clinical examination skills and communication skills, and we explore the reasons for the differences between medical schools.     

Exploring if day and time of admission is associated with average length of stay among inpatients from a tertiary hospital in Singapore: an analytic study based on routine admission data

Background  

It has been postulated that patients admitted on weekends or after office hours may experience delays in clinical management and consequently have longer length of stay (LOS). We investigated if day and time of admission is associated with LOS in Tan Tock Seng Hospital (TTSH), a 1,400 bed acute care tertiary hospital serving the central and northern regions of Singapore.     

Quantitation of prolactin receptor mRNA in the maternal rat brain during pregnancy and lactation

Prolactin receptor (PRL-R) expression in the brain is increased in lactating rats compared with non-pregnant animals. The aim of the present study was to determine the time-course of changes in PRL-R mRNA levels during pregnancy and/or lactation, and to determine relative levels of the two forms (short and/or long form) of receptor mRNA in specific brain regions. Brains were collected from female rats on dioestrus, days 7, 14 or 21 of pregnancy, day 7 of lactation or day 7 post-weaning. Frozen, coronal sections were cut (300 microm) and specific hypothalamic nuclei and the choroid plexus were microdissected using a punch technique. Total RNA was extracted and reverse transcribed, then first strand cDNA was amplified using quantitative real-time PCR. Results showed an up-regulation of long-form PRL-R mRNA in the choroid plexus by day 7 of pregnancy compared with dioestrus, which further increased on days 14 and 21 of pregnancy and day 7 of lactation, and then decreased to dioestrous levels on day 7 post-weaning. Short-form PRL-R mRNA levels increased on day 14 of pregnancy relative to dioestrus, increased further on day 7 of lactation and decreased on day 7 post-weaning. Changes in mRNA were reflected in increased levels of PRL-R immunoreactivity in the choroid plexus during pregnancy and lactation, compared with dioestrus. In the arcuate nucleus, long-form PRL-R mRNA was increased during pregnancy. In contrast to earlier work, no significant changes in short- or long-form PRL-R mRNA expression were detected in several other hypothalamic nuclei, suggesting that changes in hypothalamic mRNA levels may not be as marked as previously thought. The up-regulation of PRL-R mRNA and protein expression in the choroid plexus during pregnancy and lactation suggest a possible mechanism whereby increasing levels of peripheral prolactin during pregnancy may have access to the central nervous system. Together with expression of long-form PRL-R mRNA in specific hypothalamic nuclei, these results support a role for prolactin in regulating neuroendocrine and behavioural adaptations in the maternal brain.     

Selective non-operative management of penetrating liver injuries at a UK tertiary referral centre

Introduction

Selective non-operative management (SNOM) of penetrating abdominal injuries has increasingly been applied in North America in the last decade. However, there is less acceptance of SNOM among UK surgeons and there are limited data on UK practice. We aimed to review our management of penetrating liver injuries and, specifically, the application of SNOM.

Methods

A retrospective review was performed of patients presenting with penetrating liver injuries between June 2005 and November 2013.

Results

Thirty-one patients sustained liver injuries due to penetrating trauma. The vast majority (97%) were due to stab wounds. The median injury severity score was 14 and a quarter of patients had concomitant thoracic injuries. Twelve patients (39%) underwent immediate surgery owing to haemodynamic instability, evisceration, retained weapon or diffuse peritonism. Nineteen patients were stable to undergo computed tomography (CT), ten of whom were selected subsequently for SNOM. SNOM was successful in eight cases. Both patients who failed SNOM had arterial phase contrast extravasation evident on their initial CT. Angioembolisation was not employed in either case. All major complications and the only death occurred in the operatively managed group. No significant complications of SNOM were identified and there were no transfusions in the non-operated group. Those undergoing operative management had longer lengths of stay than those undergoing SNOM (median stay 6.5 vs 3.0 days, p<0.05).

Conclusions

SNOM is a safe strategy for patients with penetrating liver injuries in a UK setting. Patient selection is critical and CT is a vital triage tool. Arterial phase contrast extravasation may predict failure of SNOM and adjunctive angioembolisation should be considered for this group.