Fatigue and extended work hours among cardiovascular perfusionists: 2010 Survey.

Due to the emergent unpredictable nature of cardiac surgery, perfusionists, potentially, are susceptible to extended work hours and acute sleep deprivation. While fatigue among other healthcare clinicians has been studied, there has been no research on this topic specifically in the perfusion community. Therefore, the purpose of this study was to: (1) collect preliminary data on the prevalence of fatigue in perfusion and (2) identify if there were concerns regarding fatigue, performance and perfusion safety. In May 2010, a link to a 50-question survey (surveymonkey.com) was posted on Perflist and Perfmail. The survey was closed in July 2010. There were 445 respondents and data were analyzed and expressed as a response percent. Participants included 27% chief perfusionists/managers, 67% staff perfusionists, and 6.0% other (perfusion education faculty, retired perfusionists, locum tenens). Regarding extended work hours, 68.9% of surveyed perfusionists have worked at the hospital for greater than 23 hours straight and 17.5% have worked continuously for over 36 hours. Actual performance of cardiopulmonary bypass (CPB) after 17, 23, and 36 hours of wakefulness was reported by 82.9%, 63% and 14.8% respondents, respectively. Regarding bathroom requirements while on CPB, 87.5% have felt extremely uncomfortable at least once, 19.9% have relieved themselves in the operating room at least once, and 22.3% have left the pump attended by a non-perfusionist to use the restroom at least once. Microsleep during CPB was reported by 49.5% of respondents. Automobile accidents attributed to an extended period of work and fatigue was reported by 6.9% and another 44.4% reported a near-miss auto accident. A fatigue-related minor error was reported by 66% and 6.7% admit to having a serious perfusion accident believed to be due to fatigue. Concerning critical phases of bypass, 51.5% believe that they perform less effectively when fatigued. Additionally, 75.9% indicate that they have been concerned about their ability to perform their job adequately due to fatigue-related acute sleep deprivation. Opinions regarding workplace management were as follows; 48% believe that fatigue can play a role in our profession and managers should do what they can to provide a rested staff, but, unfortunately, it is impractical to set work limits; 32.2% believe fatigue issues should be taken more seriously and specific guidelines should be stated by our professional organizations and 13.4% believe that limits should be established, legislated, and enforced by state or federal authorities. Based upon this preliminary survey data, it appears that fatigue and acute sleep deprivation is a significant safety concern in the perfusion community. Further research must be performed to understand actual performance degradation that may occur in fatigued perfusionists performing CPB.

Vascular endothelial growth factor and placental growth factor release in cultured trophoblast cells under different oxygen tensions.

The oxygen status of the placenta during pregnancy is unclear although it has been hypothesised that in pre-eclampsia large regions of the placenta are hypoxic. Circulating levels of vascular endothelial growth factor (VEGF) are increased in women with pre-eclampsia, while circulating placental growth factor (PlGF) levels are decreased. We hypothesise that secreted levels of VEGF are increased in cultures of trophoblast cells under lowered oxygen conditions while secreted levels of PlGFare alternatively regulated. Primary isolates of first trimester and term cytotrophoblasts cells were cultured in 20 and 5% oxygen for 24h. There was a significant increase in the levels of VEGF secreted fromfirst trimester and term cytotrophoblast cells cultured under lowered oxygen conditions compared to the controls while there was a significant decrease in the secreted levels of PIGF in the same cell populations (as measured by ELISA). In first trimester and term trophoblast cells the presence of VEGF (121, 165 and 189) and PlGF (132 and 152) mRNA were demonstrated in both groups by reverse transcription-polymerase chain reaction (RT-PCR). These altered levels of secreted VEGF andPIGF may be released as compensatory molecules in the pathogenesis of diseases such as pre-eclampsia and intrauterine growth restriction.

The role of proteolysis in Alzheimer's disease.

Alzheimer's disease is characterised by the progressive deposition of the 4 kDa beta-amyloid peptide (A beta) in extracellular senile plaques in the brain. A beta is derived by proteolytic cleavage of the amyloid precursor protein (APP) by various proteinases termed secretases. alpha-Secretase is inhibited by hydroxamate-based zinc metalloproteinase inhibitors such as batimastat with I50 values in the low micromolar range, and displays many properties in common with the secretase that releases angiotensin converting enzyme. A cell impermeant biotinylated derivative of one such inhibitor completely blocked the release of APP from the surface of neuronal cells, indicating that alpha-secretase cleaves APP at the cell-surface. A range of hydroxamate-based compounds have been used to distinguish between alpha-secretase and tumour necrosis factor-alpha convertase, a member of the ADAMs (a disintegrin and metalloproteinase-like) family of zinc metalloproteinases. Recent data suggests that the presenilins may be aspartyl proteinases with the specificity of gamma-secretase. Although APP and the presenilins are present in detergent-insoluble, cholesterol- and glycosphingolipid-rich lipid rafts, they do not behave as typical lipid raft proteins, and thus it is unclear whether these membrane domains are the sites for proteolytic processing of APP.

Investigation of an in vitro model of trophoblast invasion.

OBJECTIVES: To re-investigate methods for visualising cytotrophoblast invasion using the Matrigel invasion model. STUDY DESIGN: Cytotrophoblast cells were isolated from pooled first trimester placentae and cultured on Matrigel-coated transwells in media supplemented with either 5 ng/ml vascular endothelial growth factor (VEGF) or 10 ng/ml epidermal growth factor (EGF). Invasion was visualised using standard and confocal fluorescent microscopy. RESULTS: The purity of the enriched cytotrophoblast cells was 84-100%. Immunofluorescent cytokeratin staining examined with an inverted fluorescent microscope suggested that cytokeratin-positive cells were present on the underside of the membrane, having invaded through the Matrigel on the upper surface. However, confocal microscopy indicated that these cells did not invade through the Matrigel, and no viable cells were identified in the culture media below the membrane. CONCLUSION: These results suggest that cytokeratin-positive staining on Matrigel-coated transwells is not necessarily indicative of cell invasion, and that similar studies should be interpreted with caution depending on the method of quantification.

The effects of angiogenic growth factors on extravillous trophoblast invasion and motility.

There is accumulating evidence that deficient trophoblast invasion of the placental bed spiral arteries is crucial to the pathogenesis of pre-eclampsia and intrauterine growth restriction. However, the factors which regulate the process of trophoblast invasion remain unclear. We have investigated whether extravillous trophoblast invasion and motility are mediated by the angiogenic growth factors, vascular endothelial growth factor (VEGF) and placental growth factor (PlGF). The SGHPL-4 extravillous trophoblast cell line was utilized. Expression of mRNA for the receptors of VEGF and PlGF (KDR and flt-1) was determined using the reverse transcriptase polymerase chain reaction. An in vitro model of invasion assessed the number and length of trophoblast processes invading into an extracellular matrix. The motility of cells under standard culture conditions was also quantified. The effect of the addition of VEGF and PlGF (+/-heparin) on trophoblast invasion and motility was determined. The effect of VEGF and PlGF (+/-heparin) on SGHPL-4 cell proliferation was assessed by cell counts at 24, 48 and 72 h post-addition of growth factor. The SGHPL-4 cells expressed mRNA for the flt-1 but not the KDR receptor. The addition of VEGF resulted in a significant decrease in the number of trophoblast processes formed (P< 0.02); this effect was not influenced by the addition of heparin. However, there was no effect on the length of processes formed in response to VEGF (+/-heparin). The addition of PlGF had no effect on either the number or the length of processes formed. The addition of VEGF increased the motility of the SGHPL-4 cells (P< 0.002); the addition of heparin prevented this VEGF-induced increase in motility. The addition of PlGF had no effect on SGHPL-4 motility (+/-heparin). Neither growth factor had any effect on the proliferative ability of SGHPL-4 cells. Contrary to our hypothesis, we did not find that the angiogenic growth factors, VEGF and PlGF, mediated the in vitro invasion of trophoblast cells into an extracellular matrix. However, VEGF did increase trophoblast motility. Our findings of an effect of VEGF on trophoblast motility (and possibly invasion) suggests the presence of functional receptors, which can mediate the actions of VEGF. Caution must be exercised before any extrapolation to the in vivo situation, however, it could be speculated that the increased motility in response to VEGF may be an initial response to attract trophoblast cells to the decidua, and that VEGF might then limit the degree to which trophoblast cells invade.

Endothelial monocyte-activating polypeptide-2 is increased in pregnancy but is not further increased in preeclampsia.

OBJECTIVES: Endothelial monocyte-activating polypeptide-2 (EMAP-2) is a novel protein that demonstrates potent proinflammatory activity in vivo and in vitro. The purpose of this study was to investigate the expression of EMAP-2 in normal pregnancy and in pregnancies complicated with preeclampsia and to test the hypothesis that EMAP-2 is a causative agent of the endothelial activation of preeclampsia. METHODS: Expression of EMAP-2 in the placenta was investigated using reverse transcriptase-polymerase chain reaction to detect mRNA, and immunohistochemistry with an EMAP-2-specific polyclonal antiserum was carried out to detect protein. Levels of circulating EMAP-2 protein were measured in the blood of nonpregnant, normal pregnant, and preeclamptic individuals using a specific enzyme-linked immunoabsorbent assay and the molecular forms present assessed by Western blotting. RESULTS: EMAP-2 is transcribed and translated by the placenta troughout pregnancy and in preeclampsia and can be detected in the plasma of nonpregnant and pregnant individuals. Levels of circulating EMAP-2 antigen are raised in pregnancy compared with nonpregnant controls; however, levels in patients with preeclampsia are identical to those in normal pregnant individuals. CONCLUSION: While circulating levels of EMAP-2 are increased in pregnancy, there is no evidence that EMAP-2 is involved directly in the pathogenesis of preeclampsia.

Patient-controlled analgesia. Experience of two new machines.

Two modern patient-controlled analgesia pumps have been evaluated in the laboratory and in clinical use. Both machines generally performed satisfactorily and patients achieved good pain relief from self-administered morphine. The relative merits of the two pumps are discussed and although the on demand analgesic computer is preferred, a substantial investment of time on the ward is required to provide continuous patient-controlled analgesia.

A quantitative analysis of the feeding behavior of suckling rabbits.

Three experiments are reported on the feeding behavior of suckling rabbits ("kittens"). In the 1st the latency with which the kittens attached to the nipple, and then left the nipple, was determined. Attachment was very rapid and wholly reliable: on the 80 tests the nipple was seized in every case in under 9 sec, and on 67 of these in less than 3 sec. The kittens also invariably left the nipple within the next minute. If the kittens were 5 or 10 days old speed of attachment was unaffected by the presence or absence of saliva on the nipple, but 15- and 20-day-old kittens seized the sucked nipples more rapidly than the unsucked nipples. In a 2nd experiment with 12-day-old kittens, washing the nipple with solvents did not affect speed of attachment; nor did saliva. The results show that suckling rabbits, in contrast to rat pups, are not heavily dependent on saliva cues. In the 3rd experiment both attachment latency and milk intake were shown to be affected by an internal stimulus, a gastric load of.9% saline, 5 g/25 g body weight: attachment latency was significantly increased and milk intake reduced by 75%.

The milk ejection of the rat, as a stimulus and a response to the litter.

A finding that the milk ejection of the rat is stimulated effectively only if at least half the pups are suckled is confirmed. This relationship, however, is found if the mother is anaesthetized but not if the mother is conscious. If the mother is conscious, the milk obtained by individual hungry pups is unaffected by the number of other hungry pups suckled. This is true whether the other pups of the litter are removed, or whether they are present but satiated. After the milk ejection, pups tend to leave the mother's nipple. Milk yield decreases with each milk ejection of a series, but getting less milk does not make the pups more likely to leave the nipple in search of another.