Motives for Sex and Sexual Perpetration in College Men: An Exploratory Study

OBJECTIVE

Prior research has rarely focused on sexual motives (e.g., motives for having sex) when studying sexual violence perpetration prevention. The current study examined the role of sexual motives alongside other risk factors like alcohol expectancies in predicting sexual violence.

METHOD

We analyzed data from 205 male college students; 36% reported sexual perpetration of some type. Participants completed a series of questionnaires in a randomized order, including: measures of prior sexual perpetration, sexual motives, rape myth acceptance, alcohol expectancies, and a measure of social desirability. Data were analyzed using a series of T-tests and logistic regressions.

RESULTS

With one exception (coping motives), all sexual motives (intimacy, enhancement, self-affirmation, peer approval, and partner approval) were endorsed at higher levels by individuals who perpetrated sexual violence than those who did not (p < .05, Cohen's d = .25-.56). The partner approval motive significantly predicted sexual violence perpetration on its own. The enhancement motive, both independently and in interaction with alcohol expectancies for aggression, predicted sexual violence perpetration. Two other motives, intimacy and self-affirmation, were only significant in interaction with alcohol expectancies for aggression.

CONCLUSION

All sexual motives were endorsed more frequently by those who perpetrated sexual violence than those who did not. Sexual motives had a complex interaction with alcohol expectancies in predicting sexual violence perpetration. The results suggest that intervention programs should emphasize healthy, consensual sexual relationships that do not involve alcohol.

Environmental niches and metabolic diversity in Neoarchean lakes

The diversification of macro-organisms over the last 500 million years often coincided with the development of new environmental niches. Microbial diversification over the last 4 billion years likely followed similar patterns. However, linkages between environmental settings and microbial ecology have so far not been described from the ancient rock record. In this study, we investigated carbon, nitrogen, and molybdenum isotopes, and iron speciation in five non-marine stratigraphic units of the Neoarchean Fortescue Group, Western Australia, that are similar in age (2.78-2.72 Ga) but differ in their hydro-geologic setting. Our data suggest that the felsic-dominated and hydrologically open lakes of the Bellary and Hardey formations were probably dominated by methanogenesis (δ¹³ C_org  = -38.7 ± 4.2‰) and biologic N₂ fixation (δ¹⁵ N_bulk  =-0.6 ± 1.0‰), whereas the Mt. Roe, Tumbiana and Kylena Formations, with more mafic siliciclastic sediments, preserve evidence of methanotrophy (δ¹³ C_org as low as -57.4‰, δ¹³ C_carb as low as -9.2‰) and NH₃ loss under alkaline conditions. Evidence of oxygenic photosynthesis is recorded only in the closed evaporitic Tumbiana lakes marked by abundant stromatolites, limited evidence of Fe and S cycling, fractionated Mo isotopes (δ^98/95 Mo = +0.4 ± 0.4‰), and the widest range in δ¹³ C_org (-57‰ to -15‰), suggesting oxidative processes and multiple carbon fixation pathways. Methanotrophy in the three mafic settings was probably coupled to a combination of oxidants, including O₂ and SO₄^2- . Overall, our results may indicate that early microbial evolution on the Precambrian Earth was in part influenced by geological parameters. We speculate that expanding habitats, such as those linked to continental growth, may have been an important factor in the evolution of life.

Validation-verification of a highly effective, practical human testicular tissue in vitro culture-cryopreservation procedure aimed to optimize pre-freeze and post-thaw motility

PURPOSE

The aim of our paper was to validate a testicular biopsy procedure that simplifies handling, processing, and cryopreservation, while at the same time optimizes sperm motility before freezing and after thawing.

METHODS

Two prospective studies were conducted to verify, optimize, and understand the virtues of pre-freeze testicular tissue IVC at different temperatures (21, 30, or 37 °C). Testicular tissue was obtained from clinical specimens designated for whole tissue cryopreservation (i.e., intact mass of tubules) and/or for fresh use in IVF-ICSI cycles. Whole testicular biopsy pieces (1-3 mm(3)) were diluted in glycerol containing freeze solutions, slow cooled to 4 °C and then rapidly frozen in LN2 vapor. Fresh and post-thaw testicular biopsy tissue were evaluated for changes in the quantity (%) and pattern of motility (I-IV: twitching to rapid progression, respectively) over a 1 week duration. The clinical effectiveness of IVC-cryopreserved whole testicular biopsy tissue was also validated analyzing fresh embryo transfers.

RESULTS

More reliable recovery of motile testicular sperm was achieved using whole tissue freeze preservation combined with IVC (24-96 h) post-acquisition at an incubation temperature of 30 °C compared to ambient temperature (21 °C) or 37 °C. Up to 85 % of the pre-freeze motility was conserved post-thaw (+3 h) for easy ICSI selection. Sperm longevity was optimized to fresh tissue levels by implementing testicular biopsy sucrose dilution post-thaw. Favorable clinical outcomes were proven using frozen-thawed testicular biopsy sperm for ICSI.

CONCLUSIONS

By employing minimal tissue manipulation, integrating pre-freeze IVC processing at 30 °C and the freezing of whole testicular biopsy tissue, we have reduced the labor and improved the efficacy of processing testicular tissue for freeze-preservation and subsequent ICSI use.

Influence of Adhesive Core Buildup Designs on the Resistance of Endodontically Treated Molars Restored With Lithium Disilicate CAD/CAM Crowns

OBJECTIVE

To assess the influence of adhesive core buildup designs (4-mm buildup, 2-mm buildup, and no buildup/endocrown) on the fatigue resistance and failure mode of endodontically treated molar teeth restored with lithium disilicate computer-aided design/computer-aided manufacturing (CAD/CAM) complete crowns placed with self-adhesive cement.

METHODS AND MATERIALS

Forty-five extracted molars were decoronated at the level of the cementoenamel junction and endodontically treated. Specimens received different Filtek Z100 adhesive core buildups (4-mm buildup; 2-mm buildup; and no buildup endocrown preparation) and were restored with Cerec 3 CAD/CAM lithium disilicate crowns (IPS e.max CAD). The intaglio surfaces of restorations (n=15) were conditioned by hydrofluoric acid etching and silane, and prepared teeth were treated with airborne-particle abrasion, followed by cementation with RelyX Unicem 2 Automix. Specimens were then subjected to cyclic isometric loading at 10 Hz, beginning with a load of 200 N (×5000 cycles), followed by stages of 400, 600, 800, 1000, 1200, and 1400 N at a maximum of 30,000 cycles each. Specimens were loaded until failure or to a maximum of 185,000 cycles. The chewing cycle was simulated by an isometric contraction (load control) applied through a 10-mm in diameter composite resin sphere (Filtek Z100). Surviving specimens were axially loaded until failure or to a maximum load of 4500 N (crosshead speed 0.5 mm/min). The failure mode was assessed, and fractures were designated as catastrophic (tooth/root fracture that would require tooth extraction) or reparable (cohesive or cohesive/adhesive fracture of restoration only). Groups were compared using the life table survival analysis (log-rank test at p=0.05). Surviving specimens were loaded to failure and compared with one-way analysis of variance.

RESULTS

The survival rates after the fatigue test were 100%, 93%, and 100% for 4-mm, 2-mm, and no buildup (endocrown), respectively and were not statistically different (only one specimen failed with a 2-mm buildup under a crown that cohesively fractured at 1,400 N). Postfatigue load to failure averaged 3181 N for 4-mm buildups (15 specimens), 3759 N for 2-mm buildups (12 specimens), and 3265 N for endocrowns (14 specimens). The 2-mm buildups were associated with higher loads to failure than endocrowns and 4-mm buildups, but no differences were found between 4-mm buildups and endocrowns (p<0.05.) One endocrown and 2 restorations with a 2-mm buildup survived the load-to-failure test (at 4500 N). Only catastrophic fractures occurred after the load-to-failure test.

CONCLUSIONS

The buildup design influenced the performance of endodontically treated molars restored with lithium disilicate CAD/CAM complete crowns placed with self-adhesive resin cement. The 2-mm buildups were associated with higher loads to failure than the endocrown and the 4-mm buildup, but all restoration designs survived far beyond the normal range of masticatory forces.

Influence of No-Ferrule and No-Post Buildup Design on the Fatigue Resistance of Endodontically Treated Molars Restored With Resin Nanoceramic CAD/CAM Crowns

Objectives

To evaluate the influence of adhesive core buildup designs—4-mm buildup, 2-mm buildup, and no buildup (endocrown)—on the fatigue resistance and failure mode of endodontically treated molar teeth restored with resin nanoceramic (RNC) CAD/CAM complete crowns placed with self-adhesive resin cement.

Methods and Materials

Forty-five extracted molars were decoronated at the level of the cementoenamel junction, and the roots were endodontically treated. Specimens received different Filtek Z100 adhesive core buildups (4-mm buildup, 2-mm buildup, and no buildup, endocrown preparation) and were restored with Cerec 3 CAD/CAM RNC crowns (Lava Ultimate). Restorations (n=15) and prepared teeth were treated with airborne-particle abrasion, followed by cementation with RelyX Unicem 2 Automix. Specimens were then subjected to cyclic isometric loading at 10 Hz, beginning with a load of 200 N (for 5000 cycles), followed by stages of 400, 600, 800, 1000, 1200, and 1400 N at a maximum of 30,000 cycles each. Specimens were loaded until failure or to a maximum of 185,000 cycles (10-mm-diameter composite resin sphere antagonist). The failure mode was assessed: “catastrophic” (tooth/root fracture that would require tooth extraction), “possibly reparable” (cohesive/adhesive failure with fragment and minor damage, chip or crack, of underlying tooth structure), or “reparable” fracture (cohesive or cohesive/adhesive fracture of restoration only). Groups were compared using the life table survival analysis. Intact specimens were loaded to failure and compared with one-way analysis of variance.

Results

All specimens survived the fatigue test until the 800 N-step. The survival rates for 4-mm, 2-mm, and no buildup (endocrown) were 53%, 87%, and 87%, respectively, and were not statistically different even though crowns with 2-mm buildups only started to fail at 1200 N. Minor cohesive chips were detected in many samples despite having survived all 185,000 cycles. Postfatigue load-to-failure ranged from 2969 N with 4-mm buildup (eight specimens), 2794 N for 2-mm buildup (13 specimens), and 2606 N for endocrowns (13 specimens) and were also not statistically different. There were only two catastrophic failures during the fatigue test and small subgingival delamination fractures and cracks (only with 4-mm buildup). All specimens in the load-to-failure test exhibited nonrestorable catastrophic fractures.

Conclusions

There was no influence of the buildup design on the performance of endodontically treated molars restored with RNC CAD/CAM complete crowns placed with self-adhesive cement. All restoration designs survived the normal range of masticatory forces. Failure mode tended to be more favorable with the 2-mm buildup or no buildup (endocrown).

Last-recorded P2Y12 reaction units value is strongly associated with thromboembolic and hemorrhagic complications occurring up to 6 months after treatment in patients with cerebral aneurysms treated with the pipeline embolization device

BACKGROUND AND PURPOSE

A recent study identified a preprocedural P2Y12 reaction units value of <60 or >240 as a strong independent predictor of perioperative thromboembolic and hemorrhagic complications after treatment of cerebral aneurysms with the Pipeline Embolization Device. This study aimed to determine whether a last-recorded P2Y12 reaction units value of <60 or >240 predicts thromboembolic and hemorrhagic complications up to 6 months after treatment of cerebral aneurysms with the Pipeline Embolization Device in the same patient cohort.

MATERIALS AND METHODS

We recorded patient and aneurysm characteristics, P2Y12 receptor antagonist administered, P2Y12 reaction units value with VerifyNow, procedural variables, and thromboembolic and hemorrhagic complications up to 6 months after Pipeline Embolization Device procedures at our institution during an 8-month period. Complications causing a permanent disabling neurologic deficit or death were considered major. Multivariate regression analysis was performed to identify independent predictors of thromboembolic and hemorrhagic complications.

RESULTS

Forty-four patients underwent 48 Pipeline Embolization Device procedures at our institution during the study period. There were 11 thromboembolic and hemorrhagic complications up to 6 months after treatment in our cohort (22.9%), 5 of which were major (10.4%). A last-recorded P2Y12 reaction units value of <60 or >240 was the only independent predictor of all (P = .002) and major (P = .03) thromboembolic and hemorrhagic complications in our cohort. Most patients (71%) required, on average, 2 adjustments to the dose or type of P2Y12 receptor antagonist to remain within the 60-240 target P2Y12 reaction units range.

CONCLUSIONS

In our cohort, a last-recorded P2Y12 reaction units value of <60 or >240 was the only independent predictor of all and major thromboembolic and hemorrhagic complications up to 6 months after Pipeline Embolization Device procedures.

Did life originate from a global chemical reactor?

Many decades of experimental and theoretical research on the origin of life have yielded important discoveries regarding the chemical and physical conditions under which organic compounds can be synthesized and polymerized. However, such conditions often seem mutually exclusive, because they are rarely encountered in a single environmental setting. As such, no convincing models explain how living cells formed from abiotic constituents. Here, we propose a new approach that considers the origin of life within the global context of the Hadean Earth. We review previous ideas and synthesize them in four central hypotheses: (i) Multiple microenvironments contributed to the building blocks of life, and these niches were not necessarily inhabitable by the first organisms; (ii) Mineral catalysts were the backbone of prebiotic reaction networks that led to modern metabolism; (iii) Multiple local and global transport processes were essential for linking reactions occurring in separate locations; (iv) Global diversity and local selection of reactants and products provided mechanisms for the generation of most of the diverse building blocks necessary for life. We conclude that no single environmental setting can offer enough chemical and physical diversity for life to originate. Instead, any plausible model for the origin of life must acknowledge the geological complexity and diversity of the Hadean Earth. Future research may therefore benefit from identifying further linkages between organic precursors, minerals, and fluids in various environmental contexts.

Diagnostic yield of catheter angiography in patients with subarachnoid hemorrhage and negative initial noninvasive neurovascular examinations

BACKGROUND AND PURPOSE

The yield of DSA in patients with SAH and negative initial noninvasive neurovascular examinations (CTA or MRA) is not well-understood. This study aimed to determine the yield of DSA for the detection of causative vascular lesions in this clinical scenario.

MATERIALS AND METHODS

We examined the yield of DSA for the detection of causative vascular lesions in a cohort of patients presenting to our institution with SAH and negative initial noninvasive neurovascular examinations during a 5-year period. Two experienced neuroradiologists independently evaluated the NCCT to determine the SAH pattern (diffuse, perimesencephalic, or peripheral sulcal) and the catheter angiograms to assess the presence of a causative vascular lesion.

RESULTS

Fifty-five patients were included in the study, with a mean age of 58.2 years (median, 58 years; range, 25-88 years). Twenty-eight patients were men (50.9%), and 27 were women (49.1%). The initial noninvasive examination was a CTA in 47 patients (85.5%) and an MRA in 8 patients (14.5%). Thirty-three patients had diffuse SAH (60%); 11, perimesencephalic SAH (20%); and 11, peripheral sulcal SAH (20%). DSA demonstrated a causative vascular lesion in 6 patients (10.9%), 5 of whom had diffuse SAH (yield of 15.2%) and 1 of whom had peripheral sulcal SAH (yield of 9.1%). No causative vascular lesions were found in patients with perimesencephalic SAH.

CONCLUSIONS

DSA is a valuable tool in the evaluation of patients with diffuse and peripheral sulcal SAH who have negative initial noninvasive neurovascular examinations, demonstrating a causative vascular lesion in 15.2% and 9.1% of patients, respectively.

271 THE EFFECT OF TEMPERATURE ON HUMAN TESTICULAR TISSUE TO OPTIMIZE THE IN VITRO MATURATION OF PRE-FREEZE MOTILITY

The development of intracytoplasmic sperm injection has made the use of testicular sperm a viable option for infertile men with obstructive and nonobstructive azoospermia. Over the past decade, testicular biopsies have been handled and processed using a variety of different methods. Whole biopsy pieces can be effectively cryopreserved in a 10% glycerol diluent (Schiewe et al. 1997 67, S115 abst); however, the ability to find viable, motile sperm post-thaw is improved when prefreeze motility exists. The purpose of this study was to comparatively document in vitro sperm motility enhancement over time at different temperatures, and to prove that an intermediate temperature (28 to 30°C) would optimize sperm longevity for up to 1 week. In this study, 10 men with obstructive azoospermia underwent a surgical, open testicular biopsy procedure. Each biopsy was placed in HEPES buffered-human tubal fluid (mHTF) medium supplemented with 5% human serum albumin (HSA; Irvine Sci., Santa Ana, CA, USA) and transported to the laboratory at room temperature. Each testis biopsy (TBx) was dissected into 8 equal pieces (approximately 2 × 2 × 1 mm). Five intact pieces of TBx were cryopreserved in separate cryovials for future use. The remaining TBx tissue was subdivided into 1 of 3 temperature treatment groups (24, 30, or 37°C) for extended IVM. The 30°C incubation condition was achieved by placing the dish(es) in a Styrofoam box placed on a 37°C warming plate. Each TBx was placed into a separate 100 × 35 mm Falcon dish in 150-μL droplets of mHTF under oil and shredded by needle dissection to disperse the contents of the seminiferous tubules. Reminant tissue was placed into another droplet for additional dissection, as needed. Sperm were analyzed for motility (graded as Type I = twitching, II = undulating, III = slow progression, and IV = rapid progression) at 0, 24, 96, and 144 h without replacing the IVM medium. The percentage increase in motility, compared with 0 h, was statistically contrasted across temperature treatments by chi-squared analysis. Testicular sperm motility ranged from 5 to 25% at 0 h and increased in all groups at 24 h. There was no difference in total motility at 24 h, but progressive motility was higher (P < 0.05) at 37°C compared with 24°C. Significant differences (P < 0.05) were observed in total percentage of motility/percentage of progressive motility at 96 h with treatment differences (*) being 30°C (66%*/44%*) > 24°C (42%*/14%) > 37°C (18%*/10%). This statistical trend continued at 144 h with 30°C (42%*/23%*) > 24°C (24%*/8%) > 37°C (9%*/5%). During this study, a viable pregnancy was achieved using a 30°C sample 8 days post biopsy, exceeding 2 previous healthy triplet pregnancies, which were successful using 4-day-old TBx specimens in 1996 and 2004. This study confirms that an intermediate IVM temperature of 30°C is optimal to enhance TBx cryopreservation, which in our laboratory is generally performed at 24 to 72 h of IVM. Our routine pregnancy success in applying ICSI with IVM, thawed TBx sperm discounts the concern some individuals express regarding DNA fragmentation of sperm over time.

Use of conventional ECG electrodes for depth of anaesthesia monitoring using the cerebral state index: a clinical study in day surgery

BACKGROUND

The cost-benefit relationship for depth of anaesthesia monitors is complicated by the high cost of specially designed EEG electrodes. The cerebral state index (CSI) monitor will accept regular ECG electrodes with snap connectors. The purpose of this study was to determine if generic ECG electrodes could replace the more expensive proprietary EEG electrodes for the CSI monitor.

METHODS

Two identical cerebral state monitors were used simultaneously during sevoflurane anaesthesia for knee arthroscopy in 14 ASA I-II patients. One monitor used proprietary (Danmeter) EEG electrodes and the other used ECG electrodes (3M Red Dot Diagnostic ECG Electrodes). Paired CSI values were recorded every other minute. Anaesthetic depth was titrated clinically. Sedation depth was scored according to the Observer's Assessment of Alertness/Sedation (OAAS) scale.

RESULTS

The agreement between the two measures was found to be high, mean difference--0.23, and the overall repeatability mean bias was 6.6 and 153/163 pairs (94%) were located within the 95% limits of agreement. No major difference was noted in impedance, noise, or artifacts. A large overlap in CSI was noted for each level of the OAAS scale; patients with CSI values as low as 40-50 responded whereas patients not responding to surgical stimulation had CSI values as high as 75. The direct cost of disposables decreased from 4euro to 0.50euro per patient by using ordinary ECG electrodes.

CONCLUSIONS

Switching from proprietary EEG electrodes to ordinary generic ECG electrodes maintains the same accuracy at about a 10th of the cost when measuring CSI during day surgery with sevoflurane anaesthesia.

The effects of fresh gas flow on the amount of sevoflurane vaporized during 1 minimum alveolar concentration anaesthesia for day surgery: a clinical study

BACKGROUND

Even small costs per case can become economically significant in high volume day surgical units. While general anaesthesia with higher fresh gas flow rates has technical advantages, they result in higher costs. The aim of the present study was to evaluate drug consumption and direct costs related to variations in the fresh gas flow and use of nitrous oxide at a 1 minimum alveolar concentration (MAC) sevoflurane end-tidal anaesthesia for day surgery.

METHODS

Thirty-two ASA I-II patients undergoing elective day surgery under general anaesthesia [14 (10-21) min] were studied. Induction was with propofol and fentanyl 100 microg. After laryngeal mask airway placement, patients were randomized to one of four different fresh gas flows: 1 or 2 l/min oxygen in air (50% oxygen), 3 l/min (33% oxygen), or 3 l/min oxygen in nitrous oxide (33% oxygen). Anaesthesia was maintained at 1 MAC. The vaporizer was weighed before and after each procedure. The primary study variable was the sevoflurane utilization per minute.

RESULTS

Sevoflurane utilization increased with increasing fresh gas flow for oxygen in air (r2 = 0.89). The nitrous oxide in oxygen group had the lowest sevoflurane utilization, even compared with the lowest oxygen in air group (0.36 vs. 0.48 g/min).

CONCLUSION

Sevoflurane utilization during 1 MAC anaesthesia increases linearly with fresh gas flow and is still higher than when nitrous oxide is used even with very low fresh gas flow rates. Direct inhaled anaesthesia-related costs are consequently 20% higher than when nitrous oxide is used, even for the lowest oxygen in air fresh gas flows.

Cerebral state index: comparison between pairwise registrations from the left and the right sides of the brain

BACKGROUND

Lateralization of cerebral blood flow and EEG activity is known to vary during cognition, sleep and waking. In spite of this, electrode placement for the cerebral state index (CSI) monitor is not specified to a particular side of the brain. This study is designed to determine if pairwise registrations differ for CSI measured simultaneously from the left or right sides of the brain.

METHODS

In total, 25 ASA I-II patients undergoing elective day surgery under general anaesthesia were recruited. Pairwise recordings were made every minute from two CSI monitors (Cerebral State Monitor, Danmeter A/S; Odense, Denmark) connected to the left and the right side of the head. Sedation was graded according to the observer's assessment of alertness/sedation rating scale and correlated with CSI.

RESULTS

A large overlap of indices, of similar magnitude, for each side of the brain was seen between different levels of sedation. The agreement between pairwise registrations was high, correlation between the 584 CSI pairs of recordings left/right was r(2)=0.92.

CONCLUSIONS

Despite known lateralization of the EEC, this study found a very high correlation in CSI derived simultaneously from the left and right sides of the brain by two independent monitors.

Cerebral state index response to incision: a clinical study in day-surgical patients

BACKGROUND

Inadequate anaesthesia, with somatic/autonomic response or awareness, is often revealed at intubation and surgical incision. Anaesthetic depth monitors should be able to prevent this risk. This explorative study examined the ability of the cerebral state monitor to predict autonomic/somatic responses to incision.

METHODS

Forty-two ASA I-II day-surgical patients [19 men and 23 females; mean age 52 (29-79) years, mean weight 77 (50-118) kg] were induced clinically with fentanyl/propofol with sevoflurane after placement of the laryngeal mask airway. The cerebral state index (CSI) was blindly recorded 4 min prior to and 4 min after incision.

RESULTS

During the 4 min prior to incision, the mean CSI was 45 (16-62) and increased by 9 (-13-40) when the mean value for the first 4 min after incision was subtracted from the value prior to incision, corresponding to a relative change of 21% (-21-118). The change in CSI did not show any consistent relation to the value before incision. Five patients showed minor movements after incision and six patients had > 25% increase in blood pressure. Neither CSI nor the change in index differed between patients who did or did not respond somatically or autonomically to incision. The last CSI value just prior to incision was 44 for non-responders and 40 and 42 for somatic and autonomic responders, respectively.

CONCLUSION

The CSI in the majority of patients was within acceptable ranges during clinically adjusted anaesthesia prior to incision but seems not to be able to reliably predict an autonomic or somatic response to incision.

Desflurane vs. sevoflurane as the main inhaled anaesthetic for spontaneous breathing via a laryngeal mask for varicose vein day surgery: a prospective randomized study

BACKGROUND

Sevoflurane has become widely used in day surgery; however, desflurane may be a valuable alternative even in this setting. This study compares emergence from anaesthesia for day surgery with spontaneous breathing using either desflurane or sevoflurane.

METHODS

This prospective, randomized, single-blinded study examined 70 ASA III patients undergoing elective ambulatory varicose vein surgery. Primary endpoint was emergence time (cessation of anaesthetic gas to communicating). Secondary endpoints included post-operative pain, nausea, time to discharge, and patient satisfaction. Patients were anaesthetized according to a standardized protocol including multimodal analgesia and antiemetic therapy and were randomized to receive sevoflurane or desflurane as the main anaesthetic while breathing spontaneously through a laryngeal mask airway. Fresh gas flow was oxygen in air 1 : 2 l/min.

RESULTS

Intra-operative anaesthesia was uneventful apart from airway irritation observed in 5/35 desflurane and 1/35 sevoflurane patients. Emergence was 25-40% faster in patients anaesthetized with desflurane. Pain and post-operative nausea and vomiting (PONV) were equally infrequent in both groups. Overall, patient satisfaction was high with no difference between the groups.

CONCLUSION

Desflurane is associated with a faster emergence with no differences during the post-operative course except a somewhat higher incidence of airway irritation.

Cerebral state monitor, a new small handheld EEG monitor for determining depth of anaesthesia

BACKGROUND AND OBJECTIVE

The cerebral state index (CSI) derived from a new small handheld electroencephalogram monitor was studied during routine day surgical anaesthesia titrated according to the bispectral index (BIS). The objective was to determine the degree of agreement between the two monitors.

METHODS

Anaesthesia was induced with propofol and fentanyl (0.1 mg) in 38 patients undergoing general anaesthesia for routine day-surgery. Maintenance anaesthesia (sevoflurane (20/38), desflurane (10/38) or propofol (8/38)) titrated by BIS XP (Aspect Medical, Natwick, MA, USA) and BIS and CSI (cerebral State Monitor, Danmeter; Odense, Denmark) index values were recorded every minute. No patient received muscle relaxation. Observer's Assessment of Alertness/Sedation rating scale was used to assess level of sedation.

RESULTS

Pair-wise recordings (914) of CSI and BIS were collected. The indices showed similar pattern and decreased with increasing level of sedation, however with large ranges for each level of sedation. Median indices were similar during surgery (BIS: 50 (14-89); CSI: 51 (7-88)) and both indices increased (P 20% from BIS-index in 24% of readings, and on rare occasions CSI indices deviated >100% from the BIS reading. When BIS < 40, CSI decreased slower than BIS and with wider spreading.

CONCLUSIONS

When used for day-surgery anaesthesia without muscle relaxation, CSI and BIS show similar patterns and numerical values but with the incidence of occasionally large discrepancies between pair-wise readings. Which monitor is the more dependable remains to be established and cannot be implied from this initial explorative study.

Cerebral state index during anaesthetic induction: a comparative study with propofol or nitrous oxide

BACKGROUND

Confidently predicting the depth of anaesthesia for the individual patient and independently of drug(s) type using EEG-based monitors has proven difficult. This open, randomized, explorative study of day surgical patients evaluates the ability of the Cerebral State Monitor (Danmeter AB, Odense, Denmark) of anaesthetic depth to identify loss of response (LOR) using either propofol or N(2)0 for induction.

METHODS

In this open, randomized study, day surgical patients (n=10 in each group) were studied using the Cerebral State Index Monitor. After baseline measurements, induction to LOR was achieved with either repeated 30-mg boluses of propofol every second minute or with N(2)0 (after premedication 5 min before with 30 mg propofol) increased every other minute in 15% increments (max. 75%). Sedation level was evaluated every other minute using the Observer's Assessment of Alertness/Sedation scale.

RESULTS

Baseline values were 91 (82-98) and 94 (82-100) for N(2)0 and propofol patients, respectively. During induction CSI decreased with increasing sedation in patients given propofol (P<0.001) but not in patients given nitrous oxide. Median value at LOR was 56 (40-76) and 95 (87-100) for the propofol and nitrous oxide group of patients, respectively.

CONCLUSION

The Cerebral State Index(trade mark) behaves as other depth of anaesthesia monitors with a progressive decrease during propofol induction but loss of consciousness with N(2)0 results in no change in CSI.

Effects of thoracic epidural analgesia on glucose homeostasis after cardiac surgery in patients with and without diabetes mellitus

BACKGROUND AND OBJECTIVE

Even moderate hyperglycaemia increases mortality/morbidity after coronary artery bypass grafting, stroke and myocardial infarction. The goal of this prospective study was to determine if using thoracic epidural analgesia from start of surgery until the end of the third postoperative day would blunt postoperative hyperglycaemia.

METHODS

Forty-four patients had diabetes mellitus, 60 did not; half of each group had an epidural with continuous local anaesthetics. All patients received continuous insulin infusions during the initial 24 h period beginning with surgery. Blood glucose was measured four times daily (fasting or 2-3 h post-prandial) until end of the third postoperative day.

RESULTS

For patients without diabetes, the epidural group had lower mean blood glucose and insulin requirements (P < 0.02) than controls during the initial 24 h period beginning with surgery. For patients with diabetes mellitus, thoracic epidural analgesia reduced mean blood glucose (P = 0.017) with unchanged insulin requirements. Epidural did not diminish the increase (vs. preoperative) in fasting blood glucose on the third postoperative day (32% vs. 22%, P < 0.001) for non-diabetics. Epidural analgesia was not able to attenuate hyperglycaemia during the first 3 postoperative days.

CONCLUSIONS

Epidural analgesia improved glucose homeostasis minimally during the initial 24 postoperative hours but did not attenuate hyperglycaemia during the subsequent 3 postoperative days.

Are even impaired fasting blood glucose levels preoperatively associated with increased mortality after CABG surgery?

AIMS

Impaired fasting glucose (IFG) below the diagnostic threshold for diabetes mellitus (DM) is associated with macrovascular pathology and increased mortality after percutaneous coronary interventions. The study goal was to determine whether pre-operative fasting blood glucose (fB-glu) is associated with an increased mortality after coronary artery bypass grafting (CABG).

METHODS AND RESULTS

During 2001-03, 1895 patients underwent primary CABG [clinical DM (CDM) in 440/1895; complete data on fB-glu for n=1375/1455]. Using pre-operative fB-glu, non-diabetics were categorized as having normal fB-glu (<5.6 mmol/L), IFG (5.6< or =fB-glu<6.1 mmol/L), or suspected DM (SDM) (> or =6.1 mmol/L). fB-glu was normal in 59%. The relative risks of 30 day and 1 year mortality compared with patients with normal fB-glu was 1.7 [95% confidence interval (CI): 0.5-5.5] and 2.9 (CI: 0.8-11.2) with IFG, 2.8 (CI: 1.1-7.2) and 1.9 (CI: 0.5-6.3) with SDM vs. 1.8 (CI: 0.8-4.0) and 1.6 (CI: 0.6-4.3) if CDM, respectively. The receiver operator characteristic area for the continuous variable fB-glu and 1 year mortality was 0.65 (P=0.002).

CONCLUSION

The elevated risk of death after CABG surgery known previously to be associated with CDM seems also to be shared by a group of similar size that includes patients with IFG and undiagnosed DM.

Clinical comparison of three different anaesthetic depth monitors during cardiopulmonary bypass

The lack of a gold standard complicates the evaluation and comparison of anaesthetic depth monitors. This randomised study compares three different depth-of-anaesthesia monitors during cardiopulmonary bypass (CPB) at 34 degrees C with fentanyl/propofol anaesthesia adjusted clinically and blinded to the monitors. Coronary artery bypass grafting patients (n = 21) were randomly assigned to all three possible paired combinations of three monitors: Bispectral Index (Aspect Medical), AAI auditory evoked potential (Danmeter), Entropy (Datex-Ohmeda). Indices were manually recorded every 5 min during CPB. Agreement between paired indices was classified as good, non-, or disagreement. Anaesthesia was classed as adequate, inadequate, or excessive according to recommended index values. Of the 255 paired indices recorded, 62% showed good agreement, 33% showed non-agreement, and 5% showed disagreement. Using good agreement between two monitors as a gold standard, a quarter of the measurements indicate inappropriate anaesthetic depth monitoring during CPB with clinically titrated anaesthetic depth.

Entropy of EEG during anaesthetic induction: a comparative study with propofol or nitrous oxide as sole agent † †This article is accompanied by Editorial I

BACKGROUND

The search continues for an anaesthetic monitor that can define the level of anaesthesia in an individual patient irrespective of anaesthetic agent(s) used. Studies of available monitors based on bispectral analysis or evoked auditory potentials show the complexity of the problem. We assessed a new monitor, based on the entropy of the EEG, during induction of anaesthesia with either propofol or nitrous oxide.

METHODS

In an open, randomized study (two groups; n=10) of day surgical patients, we induced loss of response with incremental boluses of propofol. The other group was given propofol 30 mg and then increasing concentrations of nitrous oxide until loss of response. We measured entropy with the M-Entropy Module S/5 (Datex-Ohmeda) using forehead electrodes and recorded response entropy (RE; including frontal electromyogram) and state entropy (SE; only the cortical EEG). Values are median (range).

RESULTS

Baseline values were RE 98 (96-100), SE 89 (87-91) and RE 98 (96-99), SE 89 (87-91) for the propofol and nitrous oxide patients, respectively. During propofol induction, both entropy indices decreased with increasing sedation, with RE 40 (23-76) and SE 34 (17-70) at loss of response. Neither RE nor SE decreased during nitrous oxide inhalation, and at loss of response using nitrous oxide, RE and SE were unchanged at 98 (96-100) and 88 (85-91) respectively.

CONCLUSIONS

The entropy monitor of anaesthetic depth shows a successive decrease with propofol but loss of consciousness with nitrous oxide is not associated with change in entropy indices.

Entropy during propofol hypnosis, including an episode of wakefulness

Depth of anaesthesia has proved to be a complex process to quantify. Monitors based on bispectral analysis of the electroencephalogram and auditory evoked potential have been available, but only recently has a monitor based on entropy become available. This study determined state entropy and response entropy in nine healthy volunteers during propofol hypnosis with a brief intervening period of wakefulness. Both the calculated entropy indices decreased with increasing levels of sedation (r2 = 0.58 and 0.61, respectively) and they showed a high correlation with each other (r2 = 0.94). However, an overlap was observed in real time indices between different stages of the Observer's Assessment of Alertness/Sedation Scale. Only three of the nine volunteers had explicit memories from the episode of wakefulness. Electroencephalographic entropy monitors seem to have potential for staging clinical hypnotic effects.

The AAI index, the BIS index and end-tidal concentration during wash in and wash out of sevoflurane

The bispectral index (BIS), auditory evoked potential index (AAI) and the end-tidal sevoflurane concentration were studied during induction and emergence in 10 ASA I-II patients. Both during 'wash-in' and 'wash-out' of sevoflurane, the AAI and BIS indices show huge variability and an overlap of indices between awake and not responding to command. This was the most pronounced during induction and the range of values was larger for the AAI index as compared with the BIS index. Mean (range) BIS was 85 (73-98) and 48 (10-83) awake and unconscious, respectively, and mean AAI index was 71 (43-99) and 21 (4-85), respectively. This study demonstrates the difficulties of using processed EEG variables in real time in a clinical situation of non-steady state pharmacodynamics.

Docosahexaenoic, arachidonic, palmitic, and oleic acids are differentially esterified into phospholipids of frog retina

Docosahexaenoic acid (22:6n-3) is highly enriched in the retina. To determine if retinal cells take up and metabolize fatty acids in a specific manner, retinas from Rana pipiens were incubated for 3 h with an equimolar mixture of tritiated 22:6n-3, arachidonic acid (20:4n-6), palmitic acid, and oleic acid. The radiolabeling of retinal lipids was determined and compared to the endogenous fatty acid content of the lipids. The results showed that in most, but not all, cases, the relative labeling with the four precursor fatty acids was similar to their relative abundance in each glycerolipid. Thus, during retinal glycerolipid synthesis, either through de novo or acyl exchange reactions, fatty acids are incorporated in proportions reflecting their steady-state mass levels. Since other studies with labeled glycerol have shown greater differences between early labeling patterns and molecular species mass, the final incorporation we report may be due primarily to acyl exchange reactions.

Sevoflurane requirements during ambulatory surgery: a clinical study with and without AEP-index guidance

BACKGROUND

Several monitors have been developed to measure anesthetic depth. The auditory evoked response uses an auditory signal to actively test the level of brain activity. The aim of the present study was to determine whether sevoflurane titration with A-line auditory guidance from the evoked potential monitor would reduce gas consumption and improve recovery times.

METHODS

Patients (n=60, aged 18-65 years) undergoing elective knee arthroscopy were randomized to titrate the main anesthetic sevoflurane with O2:N2O (1:2), either clinically (30 patients) or in combination with a target auditory evoked potential index of 30+/-5 (30 patients) using the A-line monitor (version 1.4, Danmeter A/S; Odense, Denmark). Induction was supplemented with fentanyl, and randomized to 0.05, 0.10 and 0.15 mg immediately before propofol (10 in each group). Sevoflurane consumption and emergence times were the primary and secondary study end-points.

RESULTS

Guidance from the A-line monitor did not reduce the sevoflurane consumption time or the emergence, regardless of the fentanyl dose. However, it did reduce the time from the recovery room to discharge eligibility (P<0.05). Sevoflurane consumption decreased inversely with the fentanyl dose (P<0.01), with no impact on emergence times.

CONCLUSION

The auditory evoked potential index provided by the A-line monitor does not decrease sevoflurane consumption or emergence times for ambulatory knee arthroscopy.

Inhalation anaesthesia is cost-effective for ambulatory surgery: a clinical comparison with propofol during elective knee arthroscopy

BACKGROUND AND OBJECTIVE

Cost consciousness has become increasingly important in anaesthesia as elsewhere in healthcare. Cost-minimization with uncompromised patient safety and quality requires systematic comparisons of alternative techniques. Inhalation anaesthesia with desflurane or sevoflurane is compared in this study with propofol delivered by the target controlled infusion technique. Directly measured drug consumption and costs and emergence times are compared.

METHODS

Consumed anaesthetics were measured during elective arthroscopy of the knee, and costs were calculated for ASA I-II patients (n = 102) randomized to 3 groups: one group received anaesthesia using propofol administered by target controlled infusion, the others inhalation anaesthesia with either desflurane or sevoflurane in combination with nitrous oxide. A partial rebreathing system was used with a laryngeal mask airway. Vaporizers were weighed before and after each anaesthetic.

RESULTS

Anaesthetic duration, postoperative pain and emesis as well as discharge time did not differ between groups. Inhaled anaesthetic techniques with desflurane or sevoflurane were associated with 2-3 min shorter emergence times (P < 0.001) and approximately 45% lower cost for consumed anaesthetics as compared with a propofol technique based on target controlled infusion. The inclusion of waste costs improved the cost reduction to 55%.

CONCLUSIONS

For this patient group, use of inhalation anaesthesia reduced drug costs by half and shortened emergence times compared to target controlled infusion with propofol with equal perioperative patient conditions.

Interaction of the insulin receptor beta-subunit with phosphatidylinositol 3-kinase in bovine ROS

PURPOSE

To identify the tyrosine-phosphorylated protein(s) in bovine rod outer segments (ROS) that are associated with phosphatidylinositol 3-kinase (PI3K).

METHODS

Glutathione-S-transferase (GST) fusion proteins containing two SH2 domains of the p85 regulatory subunit of PI3K-GST-p85 (N-SH2), GST-p85 (C-SH2), and respective SH2 mutants (N-SH2, R358A, and C-SH2, R649A)-were prepared and used to pull down tyrosine-phosphorylated proteins in bovine ROS. Protein identity was established by Western blot analysis. PI3K activity was determined in the pull-down mixtures and in immunoprecipitates by incubation with phosphatidylinositol-4,5-bisphosphate (PI-4,5-P(2)) and [gamma(32)P]adenosine triphosphate (ATP).

RESULTS

The GST pull-down assays indicated the binding of a 97-kDa protein by GST-p85 (N-SH2) in tyrosine-phosphorylated (PY)-ROS that was not present in nonphosphorylated (N)-ROS. Binding was completely abolished when the Arg 358 in the N-SH2 domain was mutated to Ala. Increased binding of the p110alpha catalytic subunit to GST-p85 (N-SH2) fusion protein was also observed in the presence of the 97-kDa phosphorylated protein. Biochemical evidence indicated that the 97-kDa protein was the beta-subunit of the insulin receptor beta-subunit (IRbeta). Immunoprecipitates of PY-ROS and N-ROS with anti-PY antibodies, probed with anti-IRbeta, indicated the presence of IRbeta only in PY-ROS. Immunoprecipitates of PY-ROS and N-ROS with anti-IRbeta antibodies, probed with anti-p85 and anti-p110alpha antibodies, indicated increased amounts of both p85 and p110alpha in PY-ROS compared to N-ROS. Treatment of ROS with insulin, followed by immunoprecipitation with either anti-IRbeta or anti-PY, resulted in increased PI3K activity. Expression and phosphorylation of the cytoplasmic tail of retina insulin receptor showed direct involvement with the p85 subunit of PI3K in vitro.

CONCLUSIONS

Tyrosine phosphorylation of the beta-subunit of the insulin receptor is involved in the regulation of PI3K activity in ROS.

Protection of photoreceptor cells in adult rats from light-induced degeneration by adaptation to bright cyclic light

Light history has been shown to affect the susceptibility of the albino rat retina to the damaging effects of constant light exposure. Retinas of animals raised in relatively bright cyclic light are protected against light-induced degeneration compared with dim-reared animals. These effects were observed in animals raised from birth in bright cyclic light and are part of an adaptive response that protects photoreceptors from stress-induced degeneration. To determine if retinas of adult animals are capable of such adaptive changes or flexibility by switching between different light environments which do not pathologically damage photoreceptor cells, albino rats were maintained in less than 250 lux cyclic light for more than 3 weeks. At 12-13 weeks of age, they were placed into 800 lux cyclic light for 1 week, after which they were exposed to constant illumination of 1500-lux for 1, 3 or 7 days. Retinal function was evaluated by electroretinography and photoreceptor cell death was quantified by measuring outer nuclear layer thickness. After 1 week in bright cyclic light, the retinas were completely protected against 1 day constant light exposure that significantly damaged retinas of animals without 800 lux cyclic light adaptation. Significant protection was also observed in 3 day constant light exposed animals; limited protection occurred after 7 days exposure. These results indicate that the retinas of adult rats adapted to bright cyclic light within certain ranges that did not significantly damage photoreceptor cells are protected from constant light challenge. This phenomenon is a post-developmental response that demonstrates a remarkable plasticity of the retina. The mechanism(s) underlying the ability of this adaptation/flexibility in protecting photoreceptors could involve endogenous molecules that encompass many aspects of retinal cell and molecular biology and physiology. Identification of these molecules may provide insight into the development of therapeutic approaches to treat retinal degeneration.

A study of bispectral analysis and auditory evoked potential indices during propofol-induced hypnosis in volunteers: the effect of an episode of wakefulness on explicit and implicit memory

The bispectral index (BIS) and the auditory evoked potential (AEP) index as calculated by the new A-line monitor were measured during hypnosis with propofol, which included an episode of wakefulness. Both indices followed a similar pattern during sedation, with values decreasing with sedation and increasing when awake. Baseline AEP values varied between 60 and 98, and BIS values were between 96 and 98. The AEP-index value was at all times 10-20 points lower than the BIS-index. The transition to loss of response occurred at a mean AEP value of 46 and BIS value of 58. The transition to just responding following a period of unconsciousness occurred at a mean AEP value of 46 and BIS 65. Both monitoring techniques, however, displayed large interindividual variations making it impossible to discriminate in real time between subtle changes of clinical state. The new neurophysiological monitors A-line AEP and BIS are interesting tools for creating a better understanding of the anaesthetic effects of drugs; however, further refinements are required before their relative roles can be fully established in the clinical setting.

Impaired synthesis of DHA in patients with X-linked retinitis pigmentosa

Many patients with X-linked retinitis pigmentosa (XLRP) have lower than normal blood levels of the long-chain polyunsaturated omega3 fatty acid docosahexaenoic acid (DHA; 22:6omega3). This clinical trial was designed to test whether down-regulation of DHA biosynthesis might be responsible for these reduced DHA levels. DHA biosynthesis was assessed in five severely affected patients with XLRP and in five age-matched controls by quantifying conversion of [U-(13)C]alpha-linolenic acid (alpha-LNA) to [(13)C]DHA. Following oral administration of [U-(13)C]alpha-LNA, blood samples were collected at designated intervals for 21 days and isotopic enrichment of all omega3 fatty acids was determined by gas chromatography/mass spectroscopy. Activity of each metabolic step in the conversion of alpha-LNA to DHA was determined by comparison of the ratios of the integrated concentration of (13)C-product to (13)C-precursor in plasma total lipid fractions. The ratio of [(13)C]DHA to [(13)C]18:3omega3 (the entire pathway) and that of [(13)C]20:5omega3 to [(13)C]20:4omega3 (Delta(5)-desaturase) were significantly lower in patients versus controls (P = 0.03 and 0.05, respectively). The estimated biosynthetic rates of [(13)C]20:5omega3, [(13)C]22:5omega3, [(13)C]24:5omega3, [(13)C]24:6omega3, and [(13)C]22:6omega3 were significantly lower in XLRP patients (42%, 43%, 31%, 18%, and 32% of control values, respectively; P < 0.04), supporting down-regulation of Delta(5)-desaturase in XLRP. The disappearance of (13)C-labeled fatty acids from plasma was not greater in XLRP patients compared with controls, suggesting that XLRP was not associated with increased rates of fatty acid oxidation or other routes of catabolism.Thus, despite individual variation among both patients and controls, the data are consistent with a lower rate of Delta(5)-desaturation, suggesting that decreased biosynthesis of DHA may contribute to lower blood levels of DHA in patients with XLRP.

Being awake intermittently during propofol-induced hypnosis: a study of BIS, explicit and implicit memory

BACKGROUND

Being awake during anaesthesia is a serious complication. An anaesthetic depth monitor must discriminate in real time between wakefulness and unconsciousness. The present study created a period of wakefulness during propofol-induced hypnosis. Bispectral index (BIS), explicit and implicit memories of the awake period were investigated.

METHODS

Ten volunteers were studied. The calculated brain concentration of a target controlled infusion of propofol was increased until loss of response (LOR) to verbal command and then propofol was stopped. When fully awake, volunteers were presented with a picture, sound and smell. Propofol infusion was restarted until LOR and then ceased. BIS and the calculated brain concentration of propofol were recorded every minute. A structured interview was conducted for explicit memories after awakening and for explicit as well as implicit memories the day after.

RESULTS

Median BIS-index for the transition between awake and asleep and vice versa differed significantly. It was not possible, however, to establish any threshold value or zone for discriminating between wakefulness and LOR due to the large inter-individual variations in BIS-index. No volunteer could explicitly recall any of the stimuli presented during the period of wakefulness.

CONCLUSION

The BIS-index decreases with increasing sedation but because of the large individual variations, the real-time BIS-index for the individual subject cannot reliably discriminate wakefulness from unconsciousness during propofol infusion. Propofol causes such profound amnesia that lack of postoperative recall does not assure that episodes of awareness have not occurred during propofol-induced hypnosis.

Low docosahexaenoic acid levels in rod outer segment membranes of mice with rds/peripherin and P216L peripherin mutations

PURPOSE

Humans with retinitis pigmentosa and dogs with progressive rod-cone degeneration (prcd) have lower than normal blood levels of long-chain polyunsaturated fatty acids, including docosahexaenoic acid (DHA), the major fatty acid found in retinal rod outer segments (ROS). In addition, prcd-affected dogs have lower levels of DHA in their ROS than control animals. The present study was designed to determine whether mice that are heterozygous for the rds mutation and transgenic mice heterozygous for a specific rds/peripherin mutation (P216L) have lower DHA levels in their ROS and other tissues than do control mice.

METHODS

Wild-type (rds(+/+)) mice, mice with the rds(-/-) (null) and rds(+/-) mutations, and mice with the P216L rds/peripherin mutation on the rds(+/-) background were maintained in the vivarium under identical husbandry conditions, and tissues were removed from each group for analysis at approximately 2 months of age. Fatty acid compositions of total lipids from plasma, red blood cells, liver, and ROS were determined by gas-liquid chromatography. ROS purity from each group was determined by SDS-PAGE with silver staining. The morphologic status of retinas representing each genotype was analyzed by light and electron microscopy.

RESULTS

There was no difference between rds(+/-), P216L on rds(+/-), and rds(+/+) (control) animals in the fatty acid composition of plasma, expressed as relative mole percent or as nanomoles fatty acid per milliliter of plasma. Small but statistically significant differences were found in 18:0 and C-22 polyunsaturated fatty acids of red blood cells. In the liver, the control animals had higher levels of 20:4n-6. In contrast, the ROS of control animals had levels of DHA that were 1.4 times that of ROS from either rds(+/-) or P216L on rds(+/-) mice of the same age. The reduction in DHA was not accompanied by an increase in 22:5n-6, which always occurs in neural tissues of animals deprived of n-3 fatty acids. SDS-PAGE of the three ROS membrane preparations showed that they were of identical purity.

CONCLUSIONS

Mice heterozygous for the spontaneous rds/peripherin mutation or mice carrying the P216L mutation on this heterozygous background have a statistically significant reduction of DHA in their ROS membranes. The authors propose that reduction in DHA is an adaptive response to metabolic stress caused by the mutation.

High serum S100B levels for trauma patients without head injuries

OBJECTIVE

Studies of patients with head trauma have demonstrated a correlation between a serum marker of brain tissue damage, namely S100B, and neuroradiological findings. It was recently demonstrated that the increases in serum S100B levels after heart surgery have extracerebral origins, probably surgically traumatized fat, muscle, and bone marrow. The current study examined multitrauma patients without head trauma, to determine whether soft-tissue and bone damage might confound the interpretation of elevated serum S100B concentrations for patients after head trauma.

METHODS

A commercial assay was used to determine serum S100B concentrations for a normal population (n = 459) and multitrauma patients without head injury (n = 17). Concentrations of the two subtypes of S100B (S100A1B and S100BB) were determined using separate noncommercial assays.

RESULTS

The mean serum S100B concentration for a normal healthy population was 0.032 microg/L (median, 0.010 microg/L; standard deviation, 0.040 microg/L). The upper 97.5% and 95% reference limits were 0.13 and 0.10 microg/L, respectively. No major age or sex differences were observed. Among trauma patients, serum S100B levels were highest after bone fractures (range, 2-10 microg/L) and thoracic contusions without fractures (range, 0.5-4 microg/L). Burns (range, 0.8-5 microg/L) and minor bruises also produced increased S100B levels. S100A1B and S100BB were detected in all samples.

CONCLUSION

Trauma, even in the absence of head trauma, results in high serum concentrations of S100B. Interpretation of elevated S100B concentrations immediately after multitrauma may be difficult because of extracerebral contributions. S100B may have a negative predictive value to exclude brain tissue damage after trauma. Similarly, nonacute S100B measurements may be of greater prognostic value than acute measurements.

Membrane protein diffusion sets the speed of rod phototransduction

Retinal rods signal the activation of a single receptor molecule by a photon. To ensure efficient photon capture, rods maintain about 109 copies of rhodopsin densely packed into membranous disks. But a high packing density of rhodopsin may impede other steps in phototransduction that take place on the disk membrane, by restricting the lateral movement of, and hence the rate of encounters between, the molecules involved. Although it has been suggested that lateral diffusion of proteins on the membrane sets the rate of onset of the photoresponse, it was later argued that the subsequent processing of the complexes was the main determinant of this rate. The effects of protein density on response shut-off have not been reported. Here we show that a roughly 50% reduction in protein crowding achieved by the hemizygous knockout of rhodopsin in transgenic mice accelerates the rising phases and recoveries of flash responses by about 1.7-fold in vivo. Thus, in rods the rates of both response onset and recovery are set by the diffusional encounter frequency between proteins on the disk membrane.