Androgens modulate autophagy and cell death via regulation of the endoplasmic reticulum chaperone glucose-regulated protein 78/BiP in prostate cancer cells.

Pro-survival signalling mediated by the androgen receptor (AR) is implicated as a key contributor to prostate carcinogenesis. As prostate tumours are characterized by nutrient-poor, hypoxic and acidified microenvironments, one mechanism whereby AR signalling may contribute to survival is by promoting adaptation to cellular stress. Here we have identified a novel role for AR in the inhibition of autophagy induced by serum withdrawal. This blockade is attributed to AR-mediated upregulation of the endoplasmic reticulum (ER) chaperone glucose-regulated protein 78/BiP (Grp78/BiP), and occurs independently of ER stress response pathway activation. Interestingly, AR activation did not affect serum starvation-induced mammalian target of rapamycin inhibition, illustrating that the adaptive role for androgens lies not in the ability to modulate nutrient sensing, but in the promotion of ER stability. Finally, we show that the adaptive advantage conferred by AR-mediated Grp78/BiP upregulation is temporary, as upon chronic serum starvation, AR activation delayed but did not suppress the onset of autophagy and cell death. This study reveals a novel mechanism whereby maintained AR signalling promotes temporary adaptation to cellular stress and in turn may contribute to the evasion of prostate tumour cell death.

Gab2 and Src co-operate in human mammary epithelial cells to promote growth factor independence and disruption of acinar morphogenesis.

The Gab2 docking protein is a target of several oncogenic protein tyrosine kinases and potentiates activation of the Ras/extracellular signal regulated kinase and phosphatidylinositol 3-kinase (PI3-kinase) pathways. Since Gab2 is phosphorylated by c-Src, and both proteins are overexpressed in breast cancers, we have determined the biological consequences of their co-expression in the immortalized human mammary epithelial cell line MCF-10A. While overexpression of c-Src did not affect acinar morphogenesis or growth factor dependence in three-dimensional culture, c-Src co-operated with Gab2 to promote epidermal growth factor (EGF)-independent acinar growth. In contrast, expression of v-Src or the activated mutant c-SrcY527F led to a spectrum of aberrant phenotypes ranging from spheroids with incomplete luminal clearance to highly disrupted, dispersed structures. Gab2 co-expression shifted the phenotypic distribution towards the dispersed phenotype, an effect not observed with a Gab2 mutant unable to bind the p85 subunit of PI3-kinase (Gab2Deltap85). In v-Src-expressing cells, Gab2, but not Gab2Deltap85, significantly decreased E-cadherin adhesive strength without altering its surface expression. Gab2 associated with E-cadherin in the presence and absence of v-Src, indicating that the ability of Gab2 to weaken the strength of cell-cell contacts may reflect enhanced activation of PI3-kinase at adherens junctions. Gab2 also increased migration and invasion of these cells in transwell assays, but these effects were p85-independent. Overall, these findings demonstrate a novel mechanism whereby Gab2 may promote metastatic spread and indicate that Gab2 may play several roles during breast cancer progression.

Influence of acute normovolaemic haemodilution on the dose-response relationship, time-course of action and pharmacokinetics of rocuronium bromide.

BACKGROUND: Acute normovolaemic haemodilution (ANH) is an effective strategy for avoiding or reducing allogeneic blood transfusion. We aimed to study its effect on the pharmacological profile of rocuronium. METHODS: In two study centres, 28 patients undergoing major surgery with ANH were matched with 28 control patients. In the dose-response groups, using the mechanomyograph, neuromuscular block of six consecutive incremental doses of rocuronium 50 microg kg(-1), followed by 300 microg kg(-1), was evaluated. In the pharmacokinetics groups, serial arterial blood samples were withdrawn for rocuronium assay after a single dose of rocuronium 600 microg kg(-1). RESULTS: ANH resulted in a shift to the left of rocuronium dose-response curve. Rocuronium effective dose(95) (ED(95)) was 26% lower (P<0.05) in the ANH group [283.4 (92.0) microg kg(-1)] compared with the control group [383.5 (127.3) microg kg(-1)]. Times from administration of last incremental dose until 25% of first response of train-of-four (TOF) recovery (Dur(25)) and 0.8 TOF ratio recovery (Dur(0.8)) were 28% longer in the ANH group [39.9 (8.4), 66.7 (14.2) min] compared with the control group [31.1 (6.6), 52.1 (15.8) min] (P<0.01, P<0.05), respectively. Volume of distribution was higher (P<0.01), central clearance was lower (P<0.05) and terminal elimination half-life was longer (P<0.0001) in the ANH group [234.97 (47.11) ml kg(-1), 4.70 (0.94) ml kg(-1) min(-1), 77.29 (12.25) min] compared with the control group [181.22 (35.73) ml kg(-1), 5.71 (1.29) ml kg(-1) min(-1), 56.86 (10.05) min, respectively]. CONCLUSION: ANH resulted in prolongation of rocuronium time-course of action, thus careful monitoring of neuromuscular block is recommended in patients who undergo ANH.

Craniofacial electromyogram activation response: another indicator of anesthetic depth.

OBJECTIVE: After finding that craniofacial EMG preceding a stimulus was a poor predictor of movement response to that stimulus, we evaluated an alternative relation between EMG and movement: the difference in anesthetic depth between the endpoint of EMG responsiveness to a stimulus and endpoint of movement responsiveness to that stimulus. We expressed this relation as the increment of isoflurane between the two endpoints. METHODS: We measured EMG over the frontalis muscle, over the corrugator muscle, and between the Fp2 and the mastoid process as patients emerged from general anesthesia during suture closing of the surgical incision. Anesthesia was decreased by controlled washout of isoflurane while maintaining 70% N2O, and brain isoflurane concentrations ((C)isoBrain) were calculated. We studied a control group of 10 patients who received only surgical stimulation, and 30 experimental patients who intermittently received test stimuli in addition to the surgical stimulation. Patients were observed for movement responses and EMG records were evaluated for EMG activation responses. We defined an EMG activation response to be a rapid voltage increase of at least 1.0 microV RMS above baseline, with a duration of at least 30 s, in at least one of the three EMG channels. Patient responses to stimuli were classified as either an EMG activation response without a move response (EMG+), a move response without an EMG activation response (MV+), both an EMG activation response and a move response (EMG+MV+), or no response. We defined the EMG+ endpoint to be the threshold between EMG+ response and nonresponse to a stimulus, and estimated (C)isoBrain at this endpoint. We similarly defined the move endpoint and estimated the move endpoint (C)isoBrain. We then calculated the increment of (C)isoBrain at the EMG+ endpoint relative to the move endpoint. MAIN RESULTS: For the 30 experimental patients, the initial response to a test stimulus was an EMG+ in 14 patients (47%), an EMG+MV+ in 12 patients (40%), and a MV+ in 1 patient (3%); no response occurred by the time surgery was completed in 3 patients (10%). No response occurred in 7 of the control patients (70%). Of the 14 patients with an initial EMG+ response to a test stimulus, 9 patients later had a move response. For these 9 patients, the increment of (C)isoBrain between the EMG+ endpoint and move endpoint was 0.11 +/- 0.04 vol%, (mean +/- SD). CONCLUSIONS: Our results suggest that, given the circumstances of our study, an EMG activation response by a nonmoving patient indicates that the patient is at an anesthetic level close to that at which movement could occur. However, because the first EMG activation response may occur simultaneously with movement, the EMG activation response cannot be relied upon to always herald a move response before it occurs. Our results also suggest that EMG responsiveness to a test stimulus may be used to estimate the anesthetic depth of an individual patient.

Subanesthetic concentrations of desflurane and propofol suppress recall of emotionally charged information.

Whether anesthetized patients register emotionally charged information remains controversial. We tested this possibility using subanesthetic concentrations of propofol or desflurane. Twenty-two volunteers (selected for hypnosis susceptibility) received propofol and desflurane (on separate occasions, and in a random order) at a concentration 1.5-2 times each individual's minimum alveolar anesthetic concentration (MAC)-awake (or equivalent for propofol). We gave vecuronium, intubated the trachea of each volunteer, controlled ventilation, and then presented a neutral (control) drama or a "crisis" drama stating that the oxygen delivery system had failed, assigning crisis and control dramas in a blinded, randomized, and balanced manner. One day later, interviewers blinded to the assigned drama conducted a 2-h structured interview (including hypnosis) to determine whether the contents of the interviews after crisis and control dramas differed. In addition, messages permitting subsequent assessment of learning of matter-of-fact information (Trivial Pursuit-type question task and a behavior task) were presented at the anesthetic concentration just sufficient to prevent response to command in each volunteer. No analyses of the tasks involving matter-of-fact information revealed learning except one which correlated hypnosis susceptibility with behavior task performance. Both propofol and desflurane suppressed memory of the crisis. Consistent with previous findings for isoflurane and nitrous oxide, propofol and desflurane suppressed learning of matter-of-fact information at concentrations just above MAC-awake, except that volunteers' susceptibility to hypnosis correlated with performance of a behavior suggested during anesthesia. Propofol and desflurane suppressed learning of emotionally charged information at anesthetic concentrations 1.5-2 times MAC-awake (less than MAC), a different result from that previously reported for ether.

Subanesthetic concentrations of desflurane and isoflurane suppress explicit and implicit learning.

The capacity of desflurane to suppress learning is unknown. We investigated whether a subanesthetic concentration of desflurane (0.6 minimum alevolar anesthetic concentration [MAC]) suppressed learning as much as the same concentration of isoflurane, and whether such suppression differed with increasing duration of anesthesia and intervening changes in anesthetic concentration. Using a cross-over-design study in 18-30 yr-old human volunteers, we supplied answers to Trivial Pursuit (Selchow & Righter Co., Bay Shore, NY)-like questions at 0.6 MAC desflurane and isoflurane before and after imposing a half-hour period at 1.7 MAC of each anesthetic, and behavioral directions and a category-example task at 0.6 MAC after the period at 1.7 MAC. These volunteers had a third anesthesia in which no information was supplied (control). After anesthesia, we tested whether the provision of answers during anesthesia increased the number of correct answers to Trivial Pursuit questions. We tested for the number of correct answers for information presented before versus after the 1.7-MAC period, for increased evocation of examples of categories presented during anesthesia, and for exhibition of a behavior suggested during anesthesia. We found that 0.6 MAC of both anesthetics prevented explicit and implicit learning before and after the period at 1.7 MAC.

The electroencephalogram does not predict depth of isoflurane anesthesia.

BACKGROUND: The power spectrum of the electroencephalogram (EEG) may be analyzed to provide quantitative measures of EEG activity (e.g., spectral edge, which defines the highest EEG frequency at which significant activity is found). The current study tested the hypothesis that spectral edge and similar measures distinguish different functional depths of anesthesia in humans. METHODS: Three groups were studied. Group 1 consisted of 34 surgical patients (ASA physical status 1 or 2) who received 0.6, 1.0 and 1.4 MAC isoflurane anesthesia. A subgroup (group 2) of group 1 was tested during 1.0 MAC isoflurane anesthesia at surgical incision. Group 3 consisted of 16 volunteers who listened to an audiotape while receiving 0.15, 0.3, and 0.45 MAC isoflurane or 0.3, 0.45, and 0.6 MAC nitrous oxide in oxygen. The audiotape contained information designed to test implicit and explicit memory formation. We tested the ability of six EEG parameters (spectral-edge, 95th percentile power frequency, median power, and zero crossing frequencies and total power in the alpha- [8-13 Hz] and delta- [< 4 Hz] power ranges) to predict movement after surgical incision, purposeful response to command, or memory of information presented during anesthetic administration. RESULTS: Isoflurane decreased EEG activity in group 1 in a dose-related fashion. The 55% of group 2 who made purposeful movements in response to incision did not differ in their EEG from nonresponders (e.g., spectral edge 19.8 +/- 3.1 vs. 19.3 +/- 2.6 Hz, mean +/- SD). In group 3, memory of the information presented did not correlate with values of any EEG parameter. Response to verbal command was associated with lower anesthetic concentrations and with smaller alpha- and delta-band power (298 +/- 66 vs. 401 +/- 80 watts; and 75 +/- 20 vs. 121 +/- 49 watts, mean +/- SD), but there was no difference in values for other parameters. CONCLUSIONS: We conclude that our EEG measures do not predict depth of anesthesia as defined by the response to surgical incision, the response to verbal command or the development of memory.

Does nitrous oxide antagonize isoflurane-induced suppression of learning?

BACKGROUND: A greater MAC fraction of nitrous oxide than isoflurane is required to prevent response to verbal commands and suppress the capacity to learn. Speculating that this difference between these agents may be caused by nitrous oxide's capacity to increase sympathetic activity, we tested the hypothesis that nitrous oxide may antagonize the suppression of learning found with isoflurane. METHODS: We administered a combination of isoflurane and nitrous oxide at three subanesthetic test concentrations (0.43, 0.56, and 0.68 MAC) to 24 healthy male volunteers. Assuming additivity of the anesthetics, the first test concentration was selected to suppress learning of new information by 50% (ED50 for suppression of learning); the second concentration, to suppress the ability to respond appropriately to verbal command by 50% (MAC-awake); and the third, to provide 1.4 times MAC-awake. Three tests of learning were applied. At each test concentration, we provided 7 answers to "trivial pursuit"-type questions, resulting in a set of 21 answered questions for each volunteer; an additional 7 unanswered questions served as controls. At the highest test concentration, each volunteer also heard two examples from each of two categories (4 words) repeated 30 times (the category-example task), and a message instructing them to touch either their nose or their ear during a specified interval in the postanesthetic interview (the behavior task). RESULTS: The MAC-awake value for the combination of isoflurane and nitrous oxide was 118 +/- 4% of the expected value (i.e., the two anesthetics were antagonistic for this effect). Consistent with antagonism, the anesthetic concentration predicted to suppress learning by 50% permitted significantly more learning, and the ED50 was 105 +/- 2% of that predicted. Neither the category task nor the behavior task demonstrated evidence of learning at 1.4 times MAC-awake. CONCLUSIONS: Our results are consistent with an antagonism between nitrous oxide and isoflurane; however, the degree of antagonism is small.

Subanesthetic concentrations of isoflurane suppress learning as defined by the category-example task.

BACKGROUND: Previously, we found unconscious (implicit) learning in subjects given subanesthetic, but not anesthetic, concentrations of isoflurane. Other investigators, using different learning tasks, have reported implicit learning at anesthetic concentrations. We investigated whether one of these tasks might provide a more sensitive test of implicit learning. In addition, to determine whether suppression of explicit or implicit learning is dose-dependent, we studied one of the tasks at three subanesthetic concentrations. METHODS: We applied a category-example task at 0.15, 0.28, and 0.4 minimum alveolar concentration (MAC) of isoflurane, and a behavior task only at 0.4 MAC. After anesthesia, we determined whether volunteers more frequently listed an example of a category (e.g., flute as an example of musical instrument) presented during anesthesia and/or demonstrated a behavior (touching ear, chin, or knee) suggested to them at 0.4 MAC. RESULTS: Results from the category task indicated implicit learning only at 0.15 MAC, a concentration that also permitted significant explicit learning. Explicit learning was demonstrated at 0.28 but not at 0.4 MAC (ED50 of 0.20 MAC and ED95 of 0.4 MAC). Results from the behavior task revealed neither implicit nor explicit learning. CONCLUSIONS: The ED50 that suppressed explicit learning in our volunteers equaled that previously reported (0.2 MAC) for implicit learning in volunteers measured using a different task. Combined, these results suggest that less than 0.45 MAC isoflurane suppresses learning in volunteers.

Effect of preoperative suggestion on postoperative gastrointestinal motility.

Autonomic behavior is subject to direct suggestion. We found that patients undergoing major operations benefit more from instruction than from information and reassurance. We compared the return of intestinal function after intra-abdominal operations in 2 groups of patients: the suggestion group received specific instructions for the early return of gastrointestinal motility, and the control group received an equal-length interview offering reassurance and nonspecific instructions. The suggestion group had a significantly shorter average time to the return of intestinal motility, 2.6 versus 4.1 days. Time to discharge was 6.5 versus 8.1 days. Covariates including duration of operation, amount of intraoperative bowel manipulation, and amount of postoperative narcotics were also examined using the statistical model analysis of covariance. An average savings of $1,200 per patient resulted from this simple 5-minute intervention. In summary, the use of specific physiologically active suggestions given preoperatively in a beleivable manner can reduce the morbidity associated with an intra-abdominal operation by reducing the duration of ileus.

Effects of isoflurane and nitrous oxide in subanesthetic concentrations on memory and responsiveness in volunteers.

Awareness, defined as conscious memory during anesthesia, has been a problem in anesthesia practice. To determine the effect of isoflurane and nitrous oxide (N2O) on memory, 17 healthy adult volunteers were randomly assigned to receive isoflurane or N2O and received the alternate agent 1-2 weeks later. Each volunteer was studied at four end-tidal concentrations of each agent, consecutively 0.15, 0.3, 0.45, and 0.15 times the minimum alveolar concentration (MAC) for isoflurane or 0.3, 0.45, 0.6, and 0.3 times MAC for N2O. After 15-min equilibration at each end-tidal concentration, volunteers were tested for voluntary response to command and were presented with verbal information to be recalled after anesthesia. Volunteers were interviewed on the day after the study and tested for conscious and unconscious memory of the information presented during anesthetic administration. MAC-awake (the end-tidal concentration preventing voluntary response in 50% of volunteers) was 0.38 (0.35-0.42) times MAC for isoflurane and 0.64 (0.61-0.68) MAC for N2O (means, 95% confidence limits), indicating isoflurane to be more potent than N2O in suppressing voluntary response (P = .0001). Memory data were analyzed in 12 volunteers who completed the study and in whom the allocation of information to be recalled was counterbalanced among agents and concentrations of agents. Memory was decreased by increasing concentrations of both agents. Conscious memory of the information presented during anesthetic administration was prevented by 0.45 MAC isoflurane but not completely prevented by 0.6 MAC N2O. Unconscious memory (defined as memory of information without conscious recognition) occurred during administration of both agents and was prevented by 0.45 MAC isoflurane but not by 0.6 MAC N2O. Isoflurane was more potent in suppressing memory than MAC-equivalent concentrations of N2O. Using models of the relationship between dose of agent and suppression of memory, a dose of both agents was estimated that suppressed memory by 50% (ED50). The ED50 was 0.20 MAC for isoflurane (95% confidence intervals, 0.15-0.25), and 0.50 MAC for N2O (95% confidence intervals 0.43-0.55). We conclude that isoflurane and N2O suppress memory in a dose-dependent manner, and that isoflurane is more potent in preventing memory and voluntary response to command than MAC-equivalent concentrations of N2O.

Isoflurane anesthesia prevents unconscious learning.

We investigated whether greater than or equal to 0.6 minimum alveolar concentration (MAC) of isoflurane suppresses learning of information presented verbally. Preoperatively, we asked 45 healthy patients (aged 23-58 yr) undergoing elective surgery 15 general knowledge questions designed to arouse their curiosity. They were told that they would be given the answers during anesthesia. Anesthesia was induced with isoflurane and nitrous oxide (25 subjects also received 1.1 +/- 0.6 mg/kg of propofol). The trachea was intubated with the aid of vecuronium (0.07 mg/kg IV). Isoflurane in oxygen was given to provide 0.6 MAC before and 1.0 and 1.4 MAC during surgery. After 10 min at each of two of the three MAC levels, the answers were given to five of the questions. At the remaining concentration, patients received a message to either touch an ear (n = 30) or keep their arms still (n = 15) during the postoperative interview. Twenty-four hours later, patients were asked whether they recalled intraoperative events. They were then asked to answer the 15 questions, choosing from five possible answers to each, one of which was correct. The number of times each patient touched an ear during this interview was noted. No patient consciously recalled events during anesthesia. The number of questions answered correctly postoperatively did not differ according to whether the answers had been provided during anesthesia (at any isoflurane concentration) or had not been provided (control questions). The number of ear-touches postoperatively did not differ between those who had and had not received the intraoperative message encouraging ear-touching.(ABSTRACT TRUNCATED AT 250 WORDS)

EEG power changes are more sensitive than spectral edge frequency variation for detection of cerebral ischemia during carotid artery surgery: a prospective assessment of processed EEG monitoring.

To investigate the basis of ambiguous reports of the validity and utility of processed electroencephalogram (EEG) detection of cerebral ischemia, 19 patients monitored during surgical procedures requiring clamping of the carotid artery were studied. The EEG was recorded and observed for detection of alteration of spectral edge frequency versus EEG power. Electrodes were positioned at the P3-C3' locations over the left hemisphere and P4-C4' areas over the right hemisphere (10-20 system of electrode placement). Maximum sensitivity was used for recordings of the processed EEG. Twelve of 19 patients had bilateral carotid vascular stenosis. Nine of 19 patients studied with EEG monitoring had EEG changes suggestive of cerebral ischemia during interruption of carotid artery blood flow by surgical manipulation, defined as a decline in EEG power of greater than 40% or a decline in spectral edge frequency of at least 3 Hz. Eight of these episodes occurred at the time of carotid vascular clamp placement. These changes were confirmed by the raw EEG. Whereas power band monitoring detected 9 episodes of suspected ischemia, alteration of spectral edge frequency was sufficient to detect only 2 of these episodes. One patient sustained a right hemispheric stroke detected intraoperatively by a 47% decline in EEG power; however, these changes were unaccompanied by intraoperative alteration of spectral edge frequency. It is concluded that monitoring of EEG power with processed EEG devices is a more sensitive indicator of cerebral ischemia than monitoring only the spectral edge frequency of the EEG.

Somatosensory evoked potentials for orthopaedic spine trauma.

Monitoring somatosensory evoked potentials (SSEPs) for intraoperative assessment of spinal cord activity provides a reliable and valid measure of sensory function during manipulation of structures placing cord function at risk. We describe a multichannel technique with artifact reductions that has proved successful in 415 spine cases including 146 posttraumatic injuries. Accurate prediction of sensory function in near or at 100% of cases is possible. No patient has recovered with less than the predicted sensory function. Statistics and cases are presented. A professional-level consultant role for SSEP monitoring is suggested as necessary for valid use of the technique.

Expressive and perceptual asymmetries of the resting face.

Lateral facial composites reveal the asymmetry of the resting face. In the current research, we created lateral composites of 30 resting faces, then had subjects compare the two composites of a face with a depiction of the whole face in either normal- or mirror-image. Results indicate that the side of the face in a subject's left visual hemi-space dominates facial recognition. The magnitude of this bias can be altered by priming tasks. It is a bias in facial perception, not memory.

Non-verbal response to intraoperative conversation.

In a double-blind study, 33 patients (herniorraphy, cholecystectomy and orthopaedic) were randomly assigned to either suggestion or control groups. Under known clinical levels of nitrous oxide and enflurane or halothane anaesthesia, suggestion patients were exposed to statements of the importance of touching their ear during a postoperative interview. Compared with controls, suggestion patients did touch their ear (tetrachoric correlation 0.61, P less than 0.001) and they did so more frequently (Mann-Whitney U test, P less than 0.02). All suggestion patients were completely amnesic for the intraoperative spoken suggestion, despite inquiries which included hypnotic regression to the operation.