Impact of bispectral index monitoring on stress response and propofol consumption in patients undergoing coronary artery bypass surgery

BACKGROUND: Bispectral Index (BIS)-titrated administration allows a reduction of propofol infusion rates in patients undergoing surgery. Resulting differences in anesthetic depth might affect the stress response to surgery involving neural circuitry not reflected in the electroencephalogram. METHODS: Forty patients scheduled to undergo elective coronary artery bypass grafting receiving a background infusion of remifentanil (0.3 microg . kg . min) were anesthetized with intravenous propofol delivered by target-controlled infusion according to the Marsh pharmacokinetic model under BIS monitoring. In a randomized, prospective design, 20 patients received propofol at a target concentration of 3 microg/ml, whereas in 20 patients propofol was titrated to maintain a BIS value of 40-50. Plasma concentrations of propofol (by means of gas chromatography-mass spectrometry), epinephrine, norepinephrine (by means of high-pressure liquid chromatography), cortisol (by means of radioimmunoassay), and interleukins 6 and 10 (by means of enzyme-linked immunosorbent assay) were measured repeatedly throughout surgery. RESULTS: BIS monitoring allowed a 30% reduction of propofol infusion rates and a similar decrease in plasma propofol concentrations in the BIS group without affecting the stress response to surgery for the group mean. None of the patients reported awareness during a standardized interview. Interestingly, propofol-remifentanil anesthesia blunted the release of epinephrine and cortisol to bypass surgery completely even when the propofol infusion rate was reduced according to BIS values. CONCLUSIONS: Total intravenous anesthesia using propofol-remifentanil effectively attenuates the neurohumoral stress response to coronary bypass surgery involving cardiopulmonary bypass. Titration of propofol using BIS allows for significant reduction of propofol consumption, with only minor effects on stress response under these conditions.     

Is surgery necessary for asymptomatic tethered cord in anorectal malformation patients?

Background

Evidence supporting routine surgery for asymptomatic tethered cord in patients with anorectal malformation (ARM) is, at best, speculative. The authors therefore examined whether untethering is indicated for asymptomatic tethered cord in patients with ARM.

Methods

A retrospective analysis of all patients with ARM (n = 223) between 1992 and 2002 was conducted. During the same period, 435 patients had surgery for tethered cord.

Results

Tethered cord was detected radiologically in 22 (9.8%); 8 patients with a low conus, and 14 with a low conus with and thickened filum. Seven of 22 patients underwent untethering; 3 prophylatic (14%) and 4 for neuro/motor function deficits (18%). All 4 symptomatic patients had significant clinical improvement in their neuro/motor functions after surgery. However, bowel and urinary functions remained unchanged in all 7 patients with a mean follow-up of 6.4 years (range, 4 to 8 years). Fifteen patients with radiologically diagnosed tethered cord remain asymptomatic with a mean follow-up of 2.7 years (range, 8 months to 10 years).

Conclusions

Neuro/motor functions clearly improved with surgery in symptomatic patients. However, bowel and urinary functions remained unchanged after surgery. Only 4 ARM patients with tethered cord required surgery, whereas prophylactic surgery appears to have minimal benefit. Expectant conservative approach in the management of asymptomatic tethered cord patient appears to be safe.     

Transurethral holmium laser enucleation of the prostate compared with transvesical open prostatectomy: 18-month follow-up of a randomized trial

PURPOSE: This ongoing randomized study aims to find out whether transurethral holmium laser enucleation of the prostate (HoLEP) could be an alternative to open transvesical prostatectomy in patients with prostates >100 g. PATIENTS AND METHODS: A series of 120 urodynamically obstructed patients were randomized to HoLEP or open prostatectomy, 60 patients to each group. The HoLEP was performed with high-powered Ho:YAG lasers at 80 to 100 W (2.0 J, 40-50 Hz) and 550-nm bare laser fibers. The American Urological Association Symptom Scores, peak urinary flow rates, and postvoiding residual urine volumes were evaluated preoperatively and at 1, 3, 6, 12, and 18 months postoperatively. All complications were noted. RESULTS: By the Mann-Whitney test, there was no significant difference between the HoLEP and open surgery groups in patient age (69.0 years HoLEP v 71.0 years open surgery), prostate volume (115 cc [range 100-230 cc] v 113 cc [100-230 cc], or weight of resected tissue (94 g [range 57-220 g] v 96 g [range 61-220 g]). There were significant differences in the mean operative time (136 v 91 minutes; P< 0.0001), mean hemoglobin loss (1.9 v 2.8 g/dL; P< 0.0001), median catheter time (1 day v 6 days; P< 0.0001), and median hospital stay (2 days v 10 days; P< 0.0001). Both HoLEP and open prostatectomy resulted in pronounced and lasting postoperative improvements in Symptom Scores, peak urinary flow rates, and postvoiding residual volumes (P< 0.0001). The differences between HoLEP and open prostatectomy were not significant at any interval for any parameter. Blood transfusions were required in 0 HoLEP patients v 8 open surgery patients. Arterial bleeding occurred in three patients in each group. Secondary apical resection was required in two HoLEP patients and no open surgery patients. Bladder neck contracture occurred in none of the HoLEP patients and two of those having open surgery. Thus, the total number of patients having complications was 7 with HoLEP and 13 with open surgery. There were no deaths in either group. CONCLUSIONS: The HoLEP appears to be an endourologic alternative to open surgical enucleation of the prostate for large glands. It entails significantly less blood loss and a much shorter catheter time and hospital stay. The perioperative outcome strongly favors the holmium procedure. The rate of late complications is equally low with each procedure. The postoperative micturition improvement was significant and lasting and was equivalent in the two groups.     

Ultrasound-induced microbubble coalescence

We studied the interaction of ultrasound contrast agent bubbles coated with a layer of lipids, driven by 0.5 MHz ultrasound. High-speed photography on the submicrosecond timescale reveals that some bubbles bounce off each other, while others show very fast coalescence during bubble expansion. This fast coalescence cannot be explained by dissipation-limited film drainage rates. We conclude that the lipid shell ruptures upon expansion, exposing clean free bubble interfaces that support plug flow profiles in the film and inertia-limited drainage whose time scales match those of the observed coalescence.     

Insulin resistance in patients with polycystic ovary syndrome

With a prevalence of 5%-10% the polycystic ovary syndrome (PCOS) is an exceptionally common disorder of premenopausal women. According to prospective studies, women with PCOS present abnormal glucose tolerance and diabetes mellitus in 31%-35% and 7.5%-10%, respectively. PCOS patients have a higher prevalence of cardiovascular risk factors such as hypertension, type 2 diabetes and dyslipidaemia. The rate of spontaneous abortions as well as the risk to develop gestational or type 2 diabetes is increased in PCOS. Therefore, PCOS is not only a reproductive problem but a complex endocrine disease with important health implications. The role of the glucose metabolism in PCOS, the health consequences and possible interventions are reviewed in this article.     

Frameless image guidance improves accuracy in three-dimensional interstitial brachytherapy needle placement

PURPOSE: The aim of this work was to adapt a computer-assisted real-time three-dimensional (3D) navigation system for interstitial brachytherapy procedures. METHODS AND MATERIALS: The 3-D navigation system Surgical Planning and Orientation Computer System (SPOCS; Aesculap, Tuttlingen, Germany) was adapted for use in interstitial brachytherapy. A special needle holder with mounted infrared-emitting diodes (IRED) for 3D navigation-based needle implantation was developed. Measurements were made on a series of different phantoms to study the feasibility and the overall accuracy and precision of the navigation system with regard to single-needle application and volume implants (multiple-needle implantations). In all, 250 single implants and 20 volume implants were performed. Accuracy was measured as the target registration error (TRE) between the preoperatively defined and the achieved target position. RESULTS: Analyses of the 250 different targets showed a mean TRE for single-needle applications of 1.1 mm (SD +/- 0.4 mm), 0.9 mm (SD +/- 0.3 mm), and 0.7 mm (SD +/- 0.3 mm) in the x, y, and z direction, respectively. The maximal deviation was 2.3 mm. The corresponding TRE in the x, y, and z direction for volume implants was 1.6 mm (SD +/- 0.4 mm), 1.9 mm (SD +/- 0.6 mm), and 1.0 mm (SD +/- 0.4 mm), respectively. The maximum deviation was 2.9 mm. CONCLUSIONS: The adaptation of a commercially available surgical planning and navigation system to interstitial brachytherapy is feasible. It enables virtual planning and improved accuracy in 3D interstitial needle implantation.     

Mitochondrial p53 levels parallel total p53 levels independent of stress response in human colorectal carcinoma and glioblastoma cells

p53 can eliminate damaged cells through the induction of mitochondria-mediated apoptosis. Recent observations have provided strong evidence that a fraction of total p53 translocates to mitochondria specifically in response to a death stimulus. Unexpectedly, mutant p53, which is expressed at much higher levels than wild type in unstressed cells, is apparently always present at the mitochondria, independent of apoptotic signal. This prompted us to ask whether cell lines with intact p53-dependent apoptosis and cell cycle arrest pathways exist in which the mitochondrial localization of wild-type p53, like that of mutant, is independent of a death stimulus and instead, correlates with the total p53 levels. Here, we document that human HCT116 colorectal carcinoma cells treated with adriamycin or 5-fluorouracil (5FU) can accumulate total p53 to equally high levels, and mitochondrial p53 to proportionate levels, although only 5FU treatment provoked p53-dependent apoptosis. Along the same line, HCT116 derivatives with increased basal p53 levels, and glioblastoma cells with a doxycycline-inducible p53, also revealed proportionate mitochondrial p53 levels, and even unstressed HCT116 cells had some p53 located at the mitochondria. Finally, mitochondrial and total p53 showed distinct post-translational modifications. Thus, cell lines exist in which the mitochondrial p53 levels parallel total levels independent of apoptosis.     

Gender-specific risk of perioperative complications in carotid endarterectomy patients with contralateral carotid artery stenosis or occlusion

Carotid endarterectomy (CEA) has been shown to be effective in stroke prevention in selected patients. Some studies, however, identified gender as an independent risk factor for perioperative CEA complications demonstrating an increased rate of perioperative stroke or death in women. Furthermore, contralateral internal carotid artery (ICA) occlusion has been associated with higher rates of perioperative CEA complications. Therefore, we sought to analyse the gender-specific risk of perioperative CEA complications between patients with or without contralateral ICA stenosis or occlusion. We retrospectively analysed 212 consecutive CEA patients (male = 156, Female = 56) for their gender-specific, perioperative risk of stroke, transient ischemic attack (TIA), restenosis and cardiac complications in the presence (62%) or absence (38%) of a contralateral ICA stenosis/occlusion. In women but not in men, risk of perioperative ischemic events (stroke, TIA) or re-stenosis (p = 0.036) and combined perioperative complications (ischemic events, re-stenosis or cardiac complications; 38.2 % vs. 9.1%; p = 0.028) was significantly increased in the presence of a contralateral ICA stenosis or occlusion. Furthermore, in the presence of a contralateral ICA stenosis/occlusion the number of perioperative ischemic events (p = 0.008) and combined perioperative complications (38.2 % vs. 14.3%; p = 0.006) was significantly higher in female than in male patients. Our study suggests that women with contralateral ICA stenosis or occlusion may have a significantly higher risk for perioperative CEA complications than other subgroups of CEA patients. This risk increase seems to be gender-specific and, if confirmed in larger prospective studies, may influence ICA stenosis therapy in the presence of a contralateral ICA stenosis/occlusion in female patients.     

Attentional blink modulation in a reaction time task: performance feedback,warning stimulus modality,and task difficulty

The present research investigated the effect of performance feedback on the modulation of the acoustic startle reflex in a Go/NoGo reaction time task. Experiment 1 (n = 120) crossed warning stimulus modality (acoustic, visual, and tactile) with the provision of feedback in a between subject design. Provision of performance feedback increased the number of errors committed and reduced reaction time, but did not affect blink modulation significantly. Attentional blink latency and magnitude modulation was larger during acoustic than during visual and larger during visual than during tactile warning stimuli. In comparison to control blinks, latency shortening was significant in all modality conditions whereas magnitude facilitation was not significant during tactile warning stimuli. Experiment 2 (n = 80) employed visual warning stimuli only and crossed the provision of feedback with task difficulty. Feedback and difficulty affected accuracy and reaction time. Whereas blink latency shortening was not affected, blink magnitude modulation was smallest in the Easy/No Feedback and the Difficult/Feedback conditions.     

Alanylation of teichoic acids protects Staphylococcus aureus against Toll-like receptor 2-dependent host defense in a mouse tissue cage infection model

Staphylococcus aureus is inherently resistant to cationic antimicrobial peptides because of alanylation of cell envelope teichoic acids. To test the effect of alanylated teichoic acids on virulence and host defense mediated by Toll-like receptor 2 (TLR2), wild-type (wt) S. aureus ATCC35556 (S.a.113) and its isogenic mutant expressing unalanylated teichoic acids (dlt(-)) were compared in a tissue cage infection model that used C57BL/6 wt and TLR2-deficient mice. The minimum infective doses (MID) to establish persistent infection with S.a.113 were 10(3) and 10(2) colony-forming units (cfu) in wt and TLR2(-/-) mice, respectively. The corresponding MID for dlt(-) were 5x105 and 10(3) cfu in wt and TLR2(-/-) mice, respectively. Both mouse strains showed bacterial-load-dependent inflammation with elevations in tumor necrosis factor, macrophage inflammatory protein 2, and leukocytes, with increasing proportions of dead cells. These findings indicate that alanylated teichoic acids contribute to virulence of S. aureus, and TLR2 mediates host defense, which partly targets alanylated teichoic acids.